My summer break starts on Monday and all I have to occupy myself is a part-time job. That’s only 8-12 hours a week, and I have no idea how to spend the rest of my time. I have to stay in Los Angeles, but otherwise I’m open to just about anything that gets me out of the house. What would you do if you had no responsibilities for three months?
I’d hang out at beaches and visit museums I’ve never seen like the Getty. Volunteer work is always available in L.A., like for the Humane Society or SPCA. If the part-time job is a total of a day or two, I’d travel the rest as much as possible. Hope you have a great break! 
Get a better job. Earn lots of money. Live happily when school starts in the fall and you have extra cash in your bank account.
My vacation starts next thursday at noon. There’s a concert in Vegas at the House of Blues at 8pm. Wanna go? Yeah, nobody else wants to go either. Think I’ll go eat worms.
Heck, you’re in LA! You’ve got a million bazillion things you could do. Your problem is going to be fitting them all into your schedule. Start with Little Tokyo for a bowl of noodles and then wander over to the LACMA annex, or whatever they call that extra bit a few blocks away from the main buildings. Art galleries and such always seem to have announcements of all the best weird stuff. Try to get lost as much as possible.