Try IL-2 Sturmovik, you can't go wrong on that one. If you are not sure about it, you can always find the demo version on COMBATSIM.
It represents the first version, but gives you a very good idea of the full game. The latest installment, IL-2 1946, regroups all previous versions.
Compared with the sims you mentioned, and which I tried myself, I think it's fair to say that IL-2 simply blows them away in nearly every field.
As for multiplayer you have Hyperlobby, which should keep you busy for some time !
Hope this was of any help to you.
