I gotta go with the classics - Aerosmith and Cheap Trick. They both have alot of great songs. I saw Aerosmith a long time ago with Dokken. I had like 5th row or something. They're amazing. Think of all the songs Aerosmith and Cheap Trick have. Since it's an 'end of school' thing - just do it. It might be a little more, but you're getting two top bands.
Let us know what you decide.