This should give you some inspiration:
Why don't you get bright colored bags from a party store, and get letter stickers from Michaels and add the names to the bags? Then maybe look for more stickers that either are the theme of the party, or match each girls personality?
If your get together allows the time and you have a table for them to work at, why not let the girls decorate their own bags? Depending on what event the bags are for, girls love to do crafts together. This gives them a project while they hang out together.