I'd be interested in playing Tony Stark. That character fits my personality and play-style well.
Though I do agree with AribethAmkiir, need to add some more female roles besides just the Black Widow. An easy way to create more female roles without adding a ton of random heroes that people new to comics haven't heard of would be to create utility roles that help drive the story. Like a female shield agent (maybe Nick Fury's right hand lady?), Betty Ross, Pepper Potts, and Jane Foster. They are all crucial female roles, and it keeps it more authentic to the setup in the movie - each man already having a woman-crush. I think as long as you stay at/around 10 people you should be fine. Pairings could look like:
Bruce Banner - Elizabeth Ross
Tony Stark - Virginia Potts
Thor Odinson - Jane Foster
Steve Rodgers - Female Agent
Natasha Romanoff - Clint Barton
Having the team operating pretty much on it's own chaotic program will reduce GM work, as you can have the crazy male characters (Tony, Hulk, Thor) push the plot and the women (Betty, Potts, SHIELD) try and keep things under control. Anyhow, the above pairings make for 10 total - and you could even scrap Pepper Potts if you want to keep numbers down - since Tony has a thing for Black Widow anyways.
The obvious team members will be, and function, as themselves. Betty Ross can be the one who keeps Hulk under control, and also a military liason. Pepper Potts can be the one in charge of Stark Tower and reigning Tony in. Jane Foster is an amazing scientist and could be working in Tony's R&D department - which would give Thor a reason to hang around more. And then perhaps Captain America could have a crush on a female SHIELD agent other than Black Widow.
Just a few ideas.