I'm not massive fan of character sheets when it comes to using established canon characters. I'm sure we know all four well enough to jump straight in, really. If it's between the Avengers and Iron Man 3 then Tony could still be recovering from 'New York', struggling with the PTSD? That could either draw them together or push them apart.

It might be interesting to have Raven return as a spy if we want to bring Erik in later, but at the same time it would be nice if she went back on her own accord because they were so close. We could, otherwise, go for the 'middle ground' approach and have her return initially to act as a spy only to realise that she'd prefer to be a member of the X-Men. There shouldn't be too much of an issue moving the events of First Class forward, particularly if neither of us are that fond of X2 or X3. 

LA might be good if Tony's still struggling with New York (though that's just a suggestion). Hmm, I don't know wheather they should have gone public or not, what do you think?