They all seem like great ideas but if it was my ds I think he would want the Monster Truck party. Hes 10 now and cars/trucks are the only toys he still will play with. He loved playing with them when he was 3.
I say let him pick. You could also do pin the eye patch on the pirate. :) I think 3-5 would be ok for a pinata. It may just take them a bit longer to crack it open. Which could be a good thing to keep them busy lol.
Thanks for the input ladies! I'd heard about the pull-string pinatas, i might try to get one- we're special ordering his pinata, haha! we're doing a monster truck theme and are gonna try to get a monster truck pinata. I'm super excited, we're gonna do wash off monster truck tattoos, a balloon/bubble dance party and pin the tail pipe on the monster truck. plus finger foods, beverages and a monster truck cake! :D am i maybe going overboard??