E.B.
A big hit at my Son's 3rd b-day were uncrustable sandwhiches (buy in the frozen section, peanut butter and jelly), they were great because you can buy in bulk if needed and by the time you are ready to serve they are thawed and they are easy for the kids to eat. I also got the pre-cut packages of apple slices as well as string cheese sticks. Then on the table I had several bowls of goldfish, pretzel sticks etc so the kids could come and go with quick easy snacks. For the parents I did sub sandwhiches and chips - easy and quick. Hope this might help!
Have fun - E.