I'm thinking the Avengers should be the government sponsored types (or the East Cost would be government sponsored, while the west coast would be corporate sponsored), while the Defenders would be more the "people's superteam" types. I'd rather they lay off the cosmic threats for a while.
Of course, the problem with these superteams made up of superheroes who can stand on their own is that there's very little chance that any single earthbound threat would require the whole team to beat, so they usually resort to cosmic threats. It's not like Power Rangers or G.I. Joe where every member has a unique skill that helps. I bet that Tony has something in his armor that would be much better than any of Hawkeye's arrows (hell, I bet his armor can shoot arrows if he wants to)
