Location, Location, Location. Changing the location of a party isn't a new idea but still is a great way to add a lot to a party. Many local museums and some shops even have spaces specifically set up for parties. If your child loves art, think about having the party at an art studio or museum. Many have spaces they use for classes that you can rent out. Or if they don't, take a tour and end outside with a picnic lunch on the lawn. Rental fees can be an added cost, but you can cut down on decorations because the venue fits the party theme.
For the Fairy Tale Party we wanted "An Enchanted Forest" and our backyard isn't super enchanting so we had the party at my aunt's farm. We found a neat area on her property among the trees and after some clearing out we had a great party space.