Hi there!
We are having our son's first birthday the 31st of this month, so I am right there with you. We ended up doing a pizza party, and at first I was against the idea, but if you are looking at having more than 10 people, it is deffinatly the way to go! We are having ours at Edwardo's, and my girlfriend is having a party on the 30th at Lou Malnatti's. Most pizza places already have party packages, and include pizza, salad, drinks and the like. It is fairly reasonable, ours is $8.95 per person, and that is for 30 people, 8 pizzas, unlimited drinks, salad and cookies. They offer a party room, and give you all the paperware you need. They even set up the room and give you a gift table, if you need it!
Let me know if this helps.
I also know of some places like Gymboree, and My Gym that do parties as well. I also was looking into the Kohl Children's Museum, and if you have a museum near you, that M. be an option as well. Lots of room for kids to play and explore, they M. have food available, and a partyroom as well. If cost is a factor, the pizza is for sure the way to go.
Good luck!
E.