As the guests leave the Bride should be the last one that speaks to them, thanking them for coming, etc. - recommend that you have them near her and have her distribute as guests come to say thier good byes to her. As the hostess for the shower you should stick close to the bride and you can hand them to her for her to give out as people leave.
that way, you aren't left with a bunch and everyone has the opportunity to speak with the guest of honor. Odds are that people will leave in cluster groups - if you and the bride are near the doorway you'll get many of them taken care of at the same time.