I also have very sweaty feet and find that all Crocs styles are wonderful. If you are looking for summer shoes or shoes for a Disney trip, go with the Beach style. This shoe is the original style and has an amazing ventilation system on the sides, top, and toe area. She will not have a problem with these. The air flows right through; it is like A/C for your feet!
As a side note, I have not worn any other shoe (literally - work, play, etc.) since I bought my first pair a few months ago. When we go to Disney in December, I am only packing my Crocs.