Everyone has memories of playing in a tub full of bubbles. I can remember my sisters and I creating "hairstyles" with the bubbles until we got bored and rinsed them out. We'd also write letters on each others' backs and try to guess what they were. My own kids had their favorite bath toys to play with. The oldest liked his plastic bath figurines and buckets, while the younger loved shoving wet washcloths into a plastic funnel, creating what he called "Benny Cakes" that he'd line up along the edge of the bathtub (I was the customer).
I find that a nice hot bubble bath is the single most relaxing activity in the world. My bathtub is my sanctuary. I chose a Japanese soaking tub before choosing a house plan. That's how serious I am about bathing. My tub is round, it's deep, it's quiet, and it's the best place I know of for total relaxation. Here's my recipe for the Ultimate Bath Experience: