I would put UP at the top of the list without any doubt. I agree with Kip, that Star Trek is pretty enjoyable as far as summer blockbuster type-y things go, but UP is by far better.
Don't see Wolverine. Just don't. This isn't coming from some elitist, snobby movie jerk, it's coming from someone who enjoyed the last three X-Men movies (even if the last one was really only redeemable because of that crazy blue lion-man). I went to see Wolverine and regretted it within the first two minutes, within which time Wolverine's sweet participation in every American war since the Civil War was relegated to the credit sequence. It really, really sucked; don't waste your money.
Terminator: Not as excruciatingly bad as Wolverine, but also not really worth it.
Angels and Demons: I haven't seen it yet, but the folks I've talked to have said it's actually BETTER than The Da Vinci Code. I kinda felt like the first one was dumb, but if you liked it then enjoy.