K.N.
Ok, so were talking 3 hours for the party.. right? My creativity works best when I have theme to coordinate with so, not sure if you have a theme but here goes... My friend threw a pirate party for her 5 yo at her house last year. It worked out extremely well... (Actually her's was a pink pirate party, for girls, but I don't think that matter much)
The kids can arrive in their favorite swashbucking attire... or just handout pirate bandanas and eye patches. One of the activities can be a treasure hunt, where you hide clues over the house and the kids were divided into 2 groups to go clue to clue until they find the treasure. It took at least 20-30 minutes for each group to go through the hunt and finally find the treasure (candy, bead necklaces, etc.). One group can jump on the moonwalk while the other hunts. She also devised a game of 'walk the plank' (with adult spotters and helping hands, of course)... That used up another 20 minutes. You can make a 'pin the X on the map' game where whomever sticks their X closest to a picture of a treasure chest wins. That's another 20 minutes. (My friend's party was in December also, so she needed activities that were more indoor.) With more moonwalk jumping and birthday cake, the 3 hours will fly by.
I'd pick up some playdough and playdough toys to amuse the younger kids.