I havent stayed onsite at
disneyland or WDW in years but I don't save or use hotel shampoo unless it is Aveda. The only place I know of that gives out Aveda is the suites at Caesars Palace, we stock up there. They come in a good size. One of the hotel chains, hilton I think it is gives out small soap bottles of nuetrogena which I also take, I like their liquid soap. Harrahs in Vegas the suites also give out round bars of gilchrist and soams I take those.
I am brand picky, so I wouldnt take just any old soap or shampoo.