We went in May of 2006 with 3 kids and 3 pairs of crocs! Kids were 3, 5, and 6 for the trip--and I agree with the poster who initially thought "$30 for those things made out of recycled junk?" LOL Worth every penny!
Our little one NEVER keeps shoes on (in fact, during 2005 trip when she was 2, she went through all 4 parks bare foot--it was awful!), but she loves her crocs!
Very light weight
Super comfortable
Perfect for airline travel (they don't make you take them off, and even they do, they are so easy to slip back on)
Can go on and off water rides
Great for kids/adults with wide feet
And yes, I wore mine all through the parks, too. Though I did switch to my Tevas when we got back to the resort.