I have no interest in the expanded stuff right now unless it's years before (Knight of the Old Republic, as an example). Yoda, Han, Chewbacca or Boba Fett prequel stuff does not sound interesting to me.
I'm really excited for Episode 7, especially if they bring back Han, Chewie, Luke, Leia, The Falcon, Lando, R2-D2 and C3-PO. I'd think they have to. Han probably would need to be written out in Episode 7, but I'd love to see him have a big role in the film. Chewie can stick around (because, not to discount Peter Mayhew, anyone can play him), as can The Falcon (though for Han to go down in the ship, it would be fitting). Lando is another character that can be written off (depending on Billy Dee Williams willingness to spend act 6-8 years from now). R2-D2 is another one (not to discount Kenny Baker) that can stick around as long as they feel his character is important. C3-PO is a tough one because Anthony Daniels is in his late 60's. He certainly can just do dialogue and let somebody else don the suit, but it's really up in the air as to whether he could do the whole trilogy. Leia could have a side role in the trilogy but Mark Hammil's involvement could range from small to large depending on what they want to do.
Obviously there will be plenty of new characters but I think there is plenty of opportunity to bring back all the main stars of the original trilogy in some fashion. It would do a good job of bridging the movies together.