A few years back, we went to the first Halloween party of the year. We are also from PA, and I also brought hotter costumes, at least for my son. I thought the nights would be cool enough for him to be tigger, which was just sweatshirt material, not the big heavy furry costume. It was well into the 80's that day, and really humid. I was in a poodle skirt costume and my DD was a 50's girl with the skirt and short skeeved shirt, and my other DD was Cinderella. My skirt had tulle under it and it was so hot and I was sweaty, and that tulle kept sticking to my legs all night. It was gross. lol I ended up putting my DS 2 in a t shirt my mom made.. she made shirts for all of us, but her, my dad and my DS wore them to the party. They were orange t shirts that she painted jackolantern faces on. I think alot of people are in costumes, but the rest are in halloween shirts.
YOu kids will be so busy with all the fun and excitement of the Halloween party, that if they arent wearing costumes, they wont notice! Just make them or buy some great boyish ( monsters, bats, skulls ) t shirts and they will fit right in. I know Target sells very cheap t shirts for halloween. get them now though!! I just bought my DS 3 one, and it said here comes trouble with lots of cute monsters, spiders, bats on it. 4 bucks!! I know they have them for the boys size 4-7 too.
Good Luck and have fun! THe party was great fun!