Our cat, Lilli (Reich), loves the tub (which is why we keep a towel in there now). Not sure if the tub-love is because that's where we bonded (we adopted kittens the same time I had surgery and had to soak in the tub several times a day). She liked to crawl down my leg and sleep on my chest (in the tub!). These days, she jumps in the tub and chatters and tweets until she gets her tummy rubbed.
Couldn't do that without a tub.