I would just advise that when deciding on a place, think of what will work best for the adults, since it sounds like will be mostly older children or adults, with very few 1 year olds. Which means that the birthday girl will probably be happy with goldfish and a cupcake and because it's a big crowd and she is so young she will probably be happiest being held a lot. Therefore don't worry about activities -- just look for a big/private space that will provide food & drink that satisfies the adult crowd, and bring your own small array of snacks for the baby/babies, and maybe a few toys from home.
At one year old the party is definitely for the family, not for the child. (I am not saying do not have a party -- it is a huge milestone and you definitely want a candle and lots of photos!) In the coming years you will have lots of opportunities for Chuck E Cheese type parties that will be more meaningful for the child.