What should I consider regarding the size of the venue?
Considering the size of the venue, you want to match it to the number of guests that you're going to have. It's that simple. Also, consider everything that you're having at the party. Don't just consider the guests. What about the band? Is it a buffet? Are you going to have some additional entertainment come over? Where are you putting your bars? Consider everything that you're having at the party, because when you know everything you're having, then you can make your layout.