We already have this game option... It's called capture the carrier. It's always seemed like a team FFA to me.
I'd like to see a capture the flag game. You could have a ring like the practice round that you fly through to "capture" the flag. You'd have to capture he enemy flag and return to your base and land to win. When you get shot down you "drop" the flag where you go down. The defending team could recapture it and return it to home base. (Wouldn't this screw with the campers!?!?)
Another game I've thought of is kinda like Noushbag's get the Noush. When I was in school we called it (sorry if this is now considered offensive, but it's what we called it) Smear the Queer. One player (maybe 1st to spawn) is declared "it" every one else is blue. Once the "it" plane gets shot down the one that killed "it" becomes "it". You win the game by either being "it" for a set period of time (maybe 2-5 minutes straight) or killing "it" a set among of times (maybe 5-10).
Edit:Sorry McF, kinda went off topic there