K.S.
She and her little friends would probably enjoy Burgerking on Barbur Blvd. , next to the retro Fred Meyer's Store. They have a huge playstructure and it's clean and well managed. I know they provide space and it's inexpensive, for B-parties, my daughter went there for one B-party and they had a blast. The address for the Burgerking is 7601 SW Barbur Blvd, Portland, OR 97219.