Nightcrawler: I can see why they didn't keep him...but I think he should have a cameo, or at the very least, he should be mentioned. Someone should say "Kurt took Jubilee out for some training" or something.
Gambit: Deserves to be in a movie more than a cameo...but idk what they'll do with him. He's an awesome character though...idk about casting either.
Beast: I've never been a big fan, and I hope he's not a huge character cause I think he's rather boring and nothing really original...however, I love the idea of having Kelsey Grammar casted as him...would've worked better if they hadnt' have had that other guy do the cameo. X-Men movies are terrible with keeping up their casting, aren't they?
Angel: I always thought Archangel was cooler...and I never liked Angel that much...and I don't see why they'll focus on him...and I don't want them to. Casting-wise, I have absolutely no idea. I just hope he isn't the main character or anything.
Stacey X or whatever that thing is: C'mon, I don't recognize it at all, must not be huge, and from what I've heard, she's pointless.
Who I'd like to see, even as much as a cameo (besides all the ones that have shown up already, of course):
Gambit, Beast, Avalanche, Blob, Sentinels (damn you for not using that, I know they won't).
Storm and Jean should be able to fly in this, and Rogue's powers should be upped, but I'd rather not have her fly yet, just use the strength or something. Maybe she can get that from Juggernaut, that'd make sense.