I like your plans, they sound fun and simple, not boring at all(:
- You could have a "Spa night", like I did for my 15th birthday party. It was a spa-themed sleepover, basically. We did the facial stuff, the hot towels, lotion--all that. Plus my step-mom is a massage therapist, so she gave us each massages. But you don't have to have a professional to do that.
- You could have it at a bowling alley, a water park, a pool, or even a putt-putt center (I've had two birthday parties at a putt-putt center. Besides the mini-golf, here are usually a bunch of arcade games, where you collect tickets from winning and use them to get little prizes and things...kind of like Chuck-E-Cheeses, but a little more advanced...at least at the one I went to.)
- A concert might also be fun, if there's anyone in your area you'd like to go see.
But like I said, it sounds like you have some good plans already. I hope whatever you decide to do works out. Happy early birthday, btw:D