If you know you are going to use it often, get the big tub.  We had a old clawfoot tub put in when we remodeled the bathroom in our old house plus walk-in shower.  Looked great and made a real statement in the bathroom, but, in the few years we lived there after the remodel, I used it once.  Was it a waste?  Not completely as I am sure it helped sale the place and we only paid $75 for it.  Would I have spent several hundred on it?  Most likely no.