16th birthday party ideas!?

I'm going to have a big birthday party bash this year for my 16th, since i haven't really had a birthday party. I'm also a dancer so im inviting everyone from my dance group, which there's 20. Not everyone is my age though...most of them are a year or two older than me. So, i don't want this to be cheesy or anything. I have no clue what to do though. I NEED HELP! Idea's please:)