We went to a birthday party for one of Mason's school friends over the weekend, and they had the cutest, simplest goodie bags.
Brown paper lunch bags with a large photocopied sticker written by the birthday girl that said "Thank you for coming to my party! Love, Abby". Then there were 4 jars set up with individually-wrapped candies and fruit snacks, so the guests could just help themselves and fill their bags with whatever they wanted!
I'm totally stealing this idea for next year's birthdays.