For a worldwide sim coverage, maybe http://www.simroutes.com helps. They choose stuff with the focus to be realistic and online ATC approved. So you can't edit routes there, but only read predefined ones with an approval.
There are also easy links and a Google Maps display added, so you find the information about the airfields and things pretty quickly.
They don't have all airports listed, but major international ones are there.

http://rfinder.asalink.net/free/ then renders some using the latest AIRAC. So it acts as a free source for current plans which, sometimes, may need a second look though.