13th B-Day Party

I am having my 13th Birthday party at an hotel in a week (its a slumber party--all girls). I was thinking that we could go swimming, go to the arcade, and watch movies, and stuff. But what if my guests get bored. What are some things that we could do?
I was thinking that I could get alot of makeup and nail polish and then let every girl pick out what they wanted and then we all do no-mirror-makeovers and the makeup would be a favor? does that sound good?
What are some other inexpensive, but nice party favors I should give?

Well thank you in advance =-]