Been meaning to check those out but haven't yet. Started over in OnAir based out of Gibraltar with no AIs to make free money for me. Just finished a cool flight toward the end of a job chain that took me around Spain and Portugal with the smooth gliiiiiiide in to some place called La Juliana, LEJU. Because I ran out of gas 8nm out. It was fucking awesome.
Also probably good that this place has 100LL cause I still need to get to Rota and then back to Gibraltar.
E: To clarify, OnAir has airports in the database that don't necessarily have Jet or 100LL (no mogas, even though Im pretty sure some of the Rotax planes in this can use it) available at the FBOs that are present. Some have both, some have one or the other, some have none or no FBOs at all. So if you are dumb and just click shit like me without checking out the airports, you end up going to places that only have the wrong type of fuel or no fuel at all, and have to either stop on the way, or work on your glider skills. If it comes down to it, you can rent/buy a plane and fly cans of fuel to wherever your plane is (or hire AIs to do this for you).
Anyhow, it uses some plugin to set your fuel levels and make sure you aren't cheating by adding gas mid flight and all that. It's pretty cool until you get in to the Longitude and can only go 500nm or whatever it is because Asobo fucked it up.