I was just about to ask the same question (not so much for trip to WDW, as just what to do in puplic.) DD is getting pretty good at using the potty at home, but those darn big seats with the opening in the front, she is just too little. The one time she did use the potty in puplic, it ended up running out of the seat and until the floor. That set us back a couple of days. Last time we were at a restant she said she had to use the potty, took one look at the big toleit seat and went in her pull up. Too make things worse she even fell in the toliet when at home, so she is worried about that. (at least it was at home when I know it was recenlty cleaned.)
Do the fold up ones fit on the large seats OK? Any one carry one around in a dipar bag? Thanks for the hint, I think I need to head out to Target or Burlington soon.