I installed two of this in my house, the deepest I could find 22".
http://www.supply.com/duravit-durastyle-soaking-bathtub-700233000000090-white-alpin/p261421

Refinish a vintage clawfoot tub. Heaven.

We bought this one for the kids' bath last year and like it very much:

http://www.faucetdirect.com/kohler-k-505-mendota-collection-60-cast-iron-three-wall-alcove-soaking-bath-tub-with-left-hand-drain/p226746?gclid=CPvOw6jVt84CFU1ZhgodPngNjw&source=gg-gba-pla_226746____40792668803&s_kwcid=AL!3775!3!40792668803!!!g!78047304408!

We did this one. Acrylic, but very nice. We bought the 72" long version . . . it's a great bath tub even for an adult.

https://www.amazon.com/KOHLER-K-1123-RA-0-Comfort-Integral-Right-Hand/dp/B0013ENJIM/ref=pd_sim_sbs_60_2?ie=UTF8&dpID=31Uv5oS5Y1L&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=M8ZKRAMNRK30P1XETHM1

I know you said not acrylic, but we recently updated our kids bathroom and used this one: https://www.amazon.com/Jacuzzi-J1S6030BRXXXXW-Signature-Soaking-Bathtub/dp/B008RAOLTG/ref=sr_1_1?ie=UTF8&qid=1466742193&sr=8-1&keywords=Jacuzzi+J1S6030BRXXXXW We are very happy with it. Nice and deep, clean modern look. We initially didn't want acrylic either, but had a hard time finding something that we liked better at a reasonable price point. Good luck!

I need a new bathtub for the kids bathroom. I don't want acrylic. I would like the tub to be a bit deeper than standard. I don't need anything fancy. Any recommendations?