What should I do for my 20th birthday party?

Hi im from chicago and I am turning 20 years old last year for my birthday I was away at school and it wasn't very Memorable i work from 3-11 at McDonald's and then went home and did a paper this year i am excited because my birthday and my spring break fall on the same day so i will be back home in chicago and my friends from school and my boyfriend are coming home with me. As you know by now i am a college student and i am kind of limited because i don't make a whole lot of money. But i did want to do something unique to chicago to show off my city and have fun I like hands on activity's like rock climbing but i have already done that before and im sure my friends have to I want to try something new and fun my friends and family can do as well. Something were they can all get to know each other, and if anyone knows of a nice restaurant downtown with good food my Favorit is seafood i would real appreciate that. An additional note chicago weather changes like ever five minutes it seems, I really like the night life and the down town seen and I have been away since aug so even if you think its old it may be new to me, I will be in a group with boys and girls. Also i am very open to new ideas and very open minded so please all ideas are welcomed