I take a bath with my DD almost every night. I usually leave my undies on, though. We did have one incident where she got a little too curious about mommy's hair "down there". OUCH!
I'd never take a shower with her; not because of the nudity, but I just know I'd slip and down we'd go.
Hubby won't take a bath with her, but mainly because that's my time with her. I have to work all day and he stays home.  

Dh takes baths with the boys not the girls. I take baths with both. Only up until they get curious.

Quoting Red-Headed Stepchild:" Last weekend I took my 1st bath w/ Sydney. It got me talking to my hubby and he says he'd never take ... [snip!] ... kids ever? Would you be opposed to your SO bathing w/ his children? At what age is it NOT appropriate to bathe w/ your kids?"

I don't think you are ever too old to bathe with your kids, as long as they aren't uncomfortable. My child is 9 and yes, she has hopped in the shower with me if we need to do something like take a shower after swimming at the rec center... or she wants to deep condition her hair with me but I need to rinse it otherwise she won't get the conditioner out. So she hops in with me. No qualms there. I don't care if my Mom or sister sees me naked. My daughter walks around naked in front of the family.

Nudity is not an issue in our family.I only make her wear clothes in front of my nephew, niece, and ex's son.

I'd bathe with my mom when I was little but never with my dad. If my SO wanted to bathe with our daughter, I probably wouldn't see anything wrong with it until she reached a certain age (although I don't see him bathing with her, he'd probably say the same as your SO).

I bathe with my 4 year old son and 1 year old daughter almost every night.

I bathed and showered with my Mom up until I was around 10, maybe even longer. Not every time, just sometimes. It was not weird to me. I would have thought it weird if my Dad had done that, but maybe that's just because I was not raised seeing him naked(thank God). Lol. Idk, I just have no desire to have memories of my Dad naked. I think that's gross :/
But I'm sure it's all very dependent upon how someone is raised as to what they think it "normal". Personally, I would bath with my kids if I didn't think it was a pain in my butt. I prefer to bath them in their own tub, I bathe DD1 and DS together. If DH wanted to bathe with DS, I'd have no problem with it. DD1, I'd have a problem with it because she is 4 and she is not his biologically, and there's really no reason for it anyway. But if he wanted to bathe with DD2, who is now just 5 months, I'd be okay with it probably until se is 2 or 3.

But DH doesn't want to bathe with any of the kids anyway, so this is something I'll never have to give serious thought to.