Never use bubble bath!! It gives me thrush!! but when i was a kid and we always used to have bubble baths, we washed with soap anyway!! not much of an answer i know but there you go!
If I've put bubbles in I don't really bother using any soap/shower gel/body wash, yet I would in the shower. Wonder if that's weird? Not that I ever have bubble baths 'cos I'm a rock hard man (cough cough).
Molton Brown and L'Occitane (and some of the other more expensive ones) do bath and shower gels combined so you can have bubbles in your bath and use it to wash with! I must admit a bath is one of my luxuries so I always buy really nce bath products.