Finalization Party Ideas...

I need advice! It looks like our adoption of a 3 and 4 year old will be finalizing this summer! YAY! We want to throw a big finalization party. We are looking at more than 100 people, adults and kids included. What have you done? Do you have any suggestions? We are thinking about having it at home, as an Open House kind of thing. Any thoughts on that? THANKS SO MUCH!!!!