You're correct, there is no waist strap on the classic Phil, it goes across the chest and stops the shoulder straps slipping off your shoulders. I had an old camelbak and used to have to hang my thumbs in the straps to stop it slippling off. The addition of the chest clip on the new one is brilliant. Size wise, I am probably the polar opposite of Bambi and to be honest I've never had a problem with it bouncing.
I have the Classic 2l version at the moment and love it. Sits comfortably on the back, has room for gels and small mobile phone etc. I also like the little strap that goes across the chest, keeps it all really secure. For around the £40 mark you really can't go wrong.
Thanks Bullit & Marty, I had looked at that one, doesn't seem to be much difference in cost between booking flght and accomodation through Disney or separately. Looks like all transfers are included if you book through them too. I think I'll go for that.