Not really DLC, but I would love to see Steam Workshop support for this game. I imagine the amount of cool user generated content that people could come up with would keep me busy for months.

more units

A more freeform gameplay mode, I don't know how campaigns in the older games played out but I felt pretty led by the nose with the priority researches and whatnot. A more civ-like approach.

All of the above.

That game kind of wore me out. I usually play Firaxis games to death but I had to push myself to actually finish this game. I don't think they could really make much to entice to play any more of it.

All of the above seems tempting, but i'll choose one for the sake of being unselfish and say i want more Additional game options or types.

Maybe more classes and skills.

The one option I miss sorely from the originals, and as a fan of horrible Sci-Fi shows, was the option to construct secondary bases, each with their own rosters and SkyRangers. Having an extended campaign where you get the option to build up beyond just having the satellite web and air bases on each continent would blow my mind.

Just imagine it, enormous cash investment to get it off the ground (or rather, deep underground), and send a veteran from your main base to lead XCOM Bravo's rookies. In return you now have the option deploy to two sites on a single day, more construction space, and a slight panic reduction for the continent you place it on. But what's that, you say? This is XCOM, you can't make the player too powerful! You're right, hypothetical voice! More invasions! More losing conditions! Introduce a new resource! Do what you need to do to make this game whoop my ass, I just want the illusion that I can be "winning" at some point to be that much more painful when the world crashes down around me.

I would like to see expansion packs. Not sure how they will do it but if they do come up with something I'll be there day one. In the running for my favourite game of 2012, which is a pleasant surprise.