I say go for the fleece, it is wonderful and looks good. If you are in the US JoAnns Fabrics has fleece on sale right now. You should also go to one of your local stores and buy a cotton mattress pad to put under the fleece.
Take a look at this thread and you can get a lot of good info.
http://www.guineapigcages.com/forum/...ect-study.html
I also suggest buying a small hand held vac (think dustbuster) so that you can just have your daughter suck out the poops every day.