Scavenger hunts are great, and with a party in October, you really have time to plan and execute a scavenger hunt that will get them out all over the neighborhood, if you want to. It's worth every bit of effort, and using creativity to get kids interacting and thinking always works better than spending extra money!
When you're out on your street, start making mental notes about the landmarks, special trees, etc. as well as the crotchety/creepy neighbors you will want your kids to avoid. Write a riddle leading the kids to each clue, and think about a nice prize for the winner and runner-up. I can't wait till my little ones are old enough for scavenger hunts. :)