The 3311Ci can be found at a great price
, and has pretty much all the useful features that the 3312Ci has (plenty of power, connections, Audyssey MultEQ XT), if AirPlay isn't that big a deal, it makes more sense. If you want to stream iTunes, an ATV is pretty cheap and more powerful anyway (ATV2 adds Netflix streaming, iTunes store, the ability to search, which is priceless if you have a large music collection, over AirTunes)
That said, the Yamaha has been getting great reviews and allows a second sub to be integrated a little more effectively. The Unit is built like a tank, has a very slick GUI, and offers a bit different of a visual aesthetic (at least Yamaha tried to make the unit look like more than an average black box). The initial set up process is a little simpler than that on Denon's, but you only have to deal with that, at most, a handful of times anyway.
Both units have plenty of power, very good reliability, are from respected companies that know how to make good equipment, and have solid video and audio credentials. Both would also benefit from a good universal remote (a la Harmony). There, I think that covers most of the disclaimers.
So here's my 1/50th of a buck. If you are thinking of a adding a second sub in the future, or really enjoy slick GUI's, get the Yamaha. If you are thinking about features v. price, get the 3311CI.