Just like the dragons have a couple unique themes, I'm really hopeful the Thalmor get their own themes when their DLC rolls around.

http://www.youtube.com/watch?v=qzRaQGsPdwk&feature=related, and something like http://www.youtube.com/watch?v=QFjotdhdBLM would be perfect in my eyes. The standard battle music already has enough variety, although I guess some new themes specifically for the Thalmor wouldn't be bad. Also, I'd love to see the Thalmor King/Emperor get his own theme as well, though I can't really make any suggestions about the "feel" of it since we don't really know what the Thalmor King/Emperor is going to be like. Whether he's just a straight up boss, secretly some sort of god-like entity, or whether he is just some dusty old man who lets his guards do his fighting.