E.C.
Do any local preschools, churches, or community centers have rooms you can rent? My experience with parties for kids around 5YO is that they'll usually enjoy simple game and craft activities. One year my friend's son's birthday party was supposed to be at a local park but we had pouring rain that weekend so they held the party at their church's social hall and the kids had a blast with what basically looked like free-play time at preschool (they were able to use the church's collection of ride-on toys and such. the other big game was batting around the balloons that were on the floor - maybe one or two popped but for the most part it was a fun activity and of course the balloons can't be thrown very hard so no one gets bonked on the head or knocked over by one), they had one craft activity, pizza and ice cream, and
Other thoughts: any local dance, gymnastics, or martial arts studios or skating rinks that have birthday party packages?