S.C.
I have found that entertainers don't really hold much attention at that age. The kids aren't paying attention for more than a few minutes and want to get up and run around. Providing something that allows the kids to entertain themselves seems to work out better - at least for my boys (2 & 4). You could try renting a bounce house/moonwalk - or maybe a blow up slide. Even my 2 year old has a blast on those things! I have rented from a company called Bouncy Biz (www.bouncybiz.com) - a friend turned me on to them.
Good luck! :-)