If you're one of those people that dreads long plane flights, this map by Matt Strimas-Mackey will help you find routes to avoid. It shows Wikipedia's list of the top 30 scheduled commercial flights by distance (with code-share duplicates removed), represented as a map showing the routes colour-coded by the time spent in the air.
Don't be distracted by the curved trajectories: these are all straight-line (technically, "great circle") routes, necessarily distorted by the use of the Kavrayskiy VII projection to fit the spherical globe onto the flat plane of your monitor. As a result, the length of the lines doesn't map exactly to the length of the route, which is why the color scale is helpful.
It's interesting to see where the routes go: if you live in eastern China or the middle-East and plan to go to the States you may well be in for a long haul. It's also interesting to see where the routes are not: as someone who's made the trip to Australia a few times I'm surprised there are only two top-25 routes there, and there being none in South America is also a surprise. Remember, too, that this chart only includes direct flights: the flight from London to Adelaide takes 19.5 hours, but requires a stop in Dubai.
Matt created this chart entirely in the R language. He used the rvest package to scrape the source data from Wikipedia. He used the ggmap package to geolocate the cities, and to generate the world map. The routes themselves were calculated by the geosphere package, which converted the great circles for display on the map projection provided by the ggalt package. For all the details on how the map was made, including the R code, follow the link to Matt's blog post below.