Re: Characters you'd like to see in future Avengers movies?
Hank and Jan along with T'Challa are a MUST!!! I think Antman/Giantman and Wasp should be introduced in their movie next and hopefully Black Panther will get a movie of their own as well before the next Avengers film.
As far as Villains go, while it's steering towards Thanos for the sequel, Hank's creation of Ultron setting up a 3rd film oughta be the way to go with the eventual creation of Vision by Ultron. If Hank doesn't appear in Film 2 then I suppose they'll go with Kang for Film 3. I'm sure Whedon wouldn't dare go ahead with Ultron without Pym's involvement.
As for Pietro and Wanda, I'd love to see them too but I can't see them appearing I'm afraid. Wouldn't mind Ms Marvel though.
"Stop, don't run it gets easier before we get carried away, and I swear you won't want to leave here once it's done, now pretend that it's only a game ...."