YOU COULD SAY I’m lucky. My parents, who raised their three children in suburban Detroit, were products of the Depression. They owned no heirlooms and harbored little interest in antiques. But they were inspired do-it-yourself decorators with a taste for quality and craftsmanship, gravitating to contemporary design from the 1960s and ’70s.  “We bought it as a floor model for 300 bucks,” my dad would bemusedly brag whenever I mentioned that the light in their living room could fetch $3,000. They had scored the iconic Arco lamp, with a marble base and swooping armature, designed in 1962 by Achille and Pier Giacomo Castiglioni.  I had long admired (OK, had my eye on) the furniture I inherited last year when my father died and my mother moved into assisted living. That lamp and their classic Milo Baughman dining set fit beautifully in my open-plan 1940s Los Angeles bungalow, and though it’s over 40 years old, the furniture has far more value—both aesthetic and emotional—than the midcentury assemblage I have created over the years.  Not all heirs are so fortunate. “Many people look at their parents’ furniture and say, ‘Ugh, how do we get rid of it?’ ” said Scott Schomer, a Los Angeles attorney who specializes in estate planning. But in an age of mass-manufactured midcentury replications and brand new “antiques,” designers contend that even the most unremarkable early 20th-century furniture and prosaic post World War II pieces—the type folks tend to leave behind—add authenticity and character to a home. “Family pieces are pregnant with meaning,” said New York interior designer Phillip Thomas, who noticed an uptick in decorating with hand-me-downs after the financial downturn of 2008.  Certainly, not every antique—technically an item at least 100 years old, a designation created in the 1930s by the U.S. Customs Office—holds financial value. New York interior designer Alan Tanks-ley put it bluntly: “Simply because things are old and purchased by people we cherished does not make them good.” For 20th-century American furniture, decorators recommend examining the manufacturer tags usually affixed to the inside of drawers. Hold on to anything labeled Herman Miller, MLHR -1.50 % Knoll, Dunbar, Bernhardt Baker, Brown Saltman and Widdicomb, among others, unless you loathe it. It’s well-constructed even if it isn’t priceless. Pieces made of bronze, brass, solid walnut, solid maple and marble are also worth finding a home for.  But no matter how sturdy or rickety a piece may be, said Mr. Thomas, “there are times when sentiment trumps everything.” And that, according to Robin Baron, current president of the Greater New York chapter of the American Society of Interior Designers, is OK. When people have a connection to objects, keeping them is “not only a design decision, it’s an emotional one, and one that needs to be respected,” she said.  So you’ve determined that a bequeathed piece is too solid or too meaningful to usher to the curb. What if it’s Arts and Crafts oak and you’re all about lacquered contemporary? Mr. Tanksley finds out-of-the-way spaces for inherited items that don’t jibe with an heir’s décor, as I have. Until I decide whether I like some of my mom and dad’s other pieces—their ornate Italianate dressers, Chinese ginger-jar lamps with pleated shades and an earth-toned fiber-art wall hanging—they’ll grace the office space in my garage.  Fortunately, however, mixing pieces of many eras and styles has rarely had as much design currency as it does today among professional designers and DIY decorators alike.  “Having too many things from one period looks static,” said Darryl Carter, a Washington, D.C., designer and author of “The Collected Home: Rooms with Style, Grace and History.” To a room dominated by antiques, he adds modern furniture and art. “And if you have a room that’s very sleek, you can put in something with a worn appearance or even something curved, carved or gilt.” For example, Mr. Carter integrated a small, handmade table made by a client’s father, who had studied with Japanese-American master woodworker George Nakashima, into a large, white, powder-coated-steel contemporary coffee table. “I had a metal artisan laser-cut an asymmetrical shape in the table’s top so the wooden piece could be inset,” said Mr. Carter.  Some family jewels do well in a prominent setting. In his Atlanta home, designer Stan Topol framed a quilt from his mother’s bedroom to hang as artwork in his sitting room. Chicago-based Julian Buckingham gave an 1870s French bedroom armoire that her husband inherited from his grandparents a star turn in her front entry, making it a coat closet. And legendary Hollywood designer William Haines often gave heirlooms—particularly ceramics and figurines—new gravity and functionality in his trademark “museum” mounted lamps: Objets sit on a wood plinth flanked by two square metal tubes that house the electrical fittings and support the shade.  Designers frequently update old furnishings with a sensitive face-lift. “Vintage and antique pieces are usually better quality than new furniture, but I see no harm in making the finish more suitable to the interior you have,” said Stephan Jones, a Beverly Hills interior designer. “Some people mistake modernizing or refinishing furniture as devaluing the piece. Think of it instead as providing the piece a longer life while also enriching it.”  “Brown furniture,” a term applied to undistinguished, medium-toned wooden pieces of any era, often calls for stripping, sanding, staining or painting. New York interior designer Timothy Whealon was unsure how to deal with sentimental brown furniture—both Georgian antiques and Edwardian reproductions—left to his sister by their mother. “The challenge was making the house feel fresh and young with these pieces,” he recalled. His solution: whitewashing wooden occasional chairs and covering them in a bold floral linen, an effect more English country-house cheerful than hand-me-down dour.  Though Mr. Carter often gives reproduction pieces the chalky appearance of Swedish Gustavian furniture by applying white gesso, he is equally partial to ebonizing. For a Washington, D.C., dining room, he covered a client’s sentimental brown breakfront with black paint, then gussied it up with new hardware and a white Carrara marble top. “While it may be sacrilege to the purist, adding a stone top in a contrasting color honors a piece and makes it feel more a part of the present,” he noted, “and it can be done affordably by buying a remnant at a stone yard.”  Rachel Laxer, who works in London and New York, also believes in “going magic black.” She transformed a midcentury Herman Miller office cabinet her parents gave her into an entry console by lacquering it and adding a black glass top. Except for museum-quality furniture, she explained, “everything looks better when you put black glossy paint on it.” French Provincial furniture, another common 1960s left-behind style, benefits greatly from paint. “I re-lacquered an ornate French headboard in teal for a beach-house bedroom, and that really kicked it up,” said New York designer Wesley Moon.  What about Grammy’s somewhat ghastly Victorian parlor sofa and chairs? “Cover them in a simple fabric that allows the frame and details to shine,” suggested Ms. Laxer, “and pair them with a more-modern coffee table.” For a basic bench or dining chairs with padded seats of any era, she opts for a vivid leather covering, an upgrade that can be mastered with scissors, a screwdriver and a staple gun.  Mr. Carter added that reproductions of ye olde American Colonial and Federal styles, popular throughout the 1950s and ’60s, often have classical bones. “If a wing chair is in damask or orange rayon, forget about the fabric and focus on the silhouette of the piece and its scale,” said Mr. Carter. “Recovered in linen, it can be shockingly sublime.” With traditional skirted chairs and sofas, he suggested removing the fabric to reveal the legs, a look more suitable to contemporary homes.  With some tweaks, obstinately eccentric pieces can be made sympathetic in even the most minimalist rooms, said Todd Nickey of L.A. design firm Nickey Kehoe, which worked with a client who had inherited a pair of late 1960s American dressers with a Spanish motif. “She wasn’t crazy about them, but they were the only remembrances she had, so we painted them in a creamy gray-white and used them as nightstands,” he explained. They were the most ornate pieces in the room, yet they blended in with the white walls for a modern look.  Sometimes the necessity of including inherited pieces gives birth to more than cosmetic innovation. When presented with one client’s 1960s glass-topped wooden coffee table, West Hollywood designer Tommy Chambers removed the glass, stripped and stained the table, then added a top cushion and bolster to create a daybed. At home, Mr. Chambers mounted to his dining-room wall the Japanese sword chest in which his grandfather had stored tools, creating a floating sideboard with room on top for a drinks bar.  For a living-room revamp, Mr. Moon was asked to include an antique Chinese panel a client’s husband had acquired from his mother. “It was just too bulky and heavy to work hanging up,” he recalled, “but it was the perfect size for a coffee table.” To protect and showcase the intricate wood carving, he encased it in a frame of polished steel and glass, turning what might have been a cumbersome decoration into a conversation piece.  “Integrating a family heirloom adds warmth and history,” he noted. “It’s good to have these things, however quirky they may be, as long as they are loved and make my clients feel at home.”
You might think the beloved-but-dated sofas and tables you’ve inherited can’t possibly fit into the style of your home. But as interior designers have learned, where there’s a will, there’s usually a way.