My boys can all still fit in our large bathtub together. Once we add the plastic animals and the foam alphabet letters, it's gettting to be a close squeeze, but they can do it. The boys all manage to get along in there, even with J. lying down and flopping around in order to be the "big, white seal" (a favorite from our last aquarium visit).
The twins always perk up once they hit the water. In the living room they may have had the million-mile stare, especially if any music has been playing (I am in a quandary about playing CD's for them, because if they like the music they stop playing, interacting and sometimes stop moving at all, often for the duration of the CD) In the warm water of the tub, on the other hand, their faces brighten, they babble, they play with animals or splash around.
The best part comes after ten or fifteen minutes, when one or the other will come up to the edge of the tub, look right into my eyes and laugh with me. G. has even taken to giving me kisses. B. will grab on to my hair or my shirt, and just smile right at me.