I loved the game Hind (1996, from Digital Integration). Of course, it wasn't very realistic, with gunner and pilot rolled into one, but the great range of missions (airlift, CAS, SAR etc) made it a blast.
So I'm in the Black Hawk camp. Figure, an US chopper next together with a Russian aircraft, would be great for the DCS range. Of course, AI isn't perfect. But so what? Look at Shogun 2: Total War. You can select in the single player campaign "I'll do my battles against AI, but if a real life opponent is available on internet and willing, he can drop in and join in".
Such an option would be great in DCS. "OK, I have time to fly. Single player? Nah, first let's see what's available. Hey! I can join in as co-pilot here, pilot there or gunner in these two games. Mmmmm."
(Ahhh, Milene beat me to it!)