I would choose a more fun shower curtain and use a color from it for the walls probably a green of some kind since this space does not say kid to me. I have no idea about the kids so this is just ideas Both of which have the beige from the counter and the green I would use

I would do a soft cream that coordinates with the floor and shower tiles. Then, add fresh color in the shower curtain, towels, rugs, and artwork. Hard to say what color since you don't give ages of children...

Thanks Sammie! My kids are all little 3-8yrs