Can someone tell me what places I could go in Boston for my 18th birthday?

Okay so I want to go to Boston for my 18th birthday. I'm going with my 3 best friends and my family and my friends family...so it's a lot of people. I know I want to do are horseback riding so if anyone can recommend a good place they know that for that would be good. Also, I need to find a teen club because my 2 friends are still under aged. But otherwise i'm lost so if anyone else could recommend any other places, towns, or things we could do that would be great and I'd really appreciate it. thanks !!