I find ancient baths fascinating. I'm specifically looking for a book that also has images of the baths, ESPECIALLY if it also has good images of what they may have looked like at the time. I'd love to read about and see what the Terme di Caracalla might have looked like, for example. So yeah, looking for a book like that.
There has been loads written on Roman bathing - perhaps unsurprisingly, considering how important it was in Roman social and cultural life. The best books are these:
J. Delaine, The Baths of Caracalla
G. Fagan, Bathing in Public in the Roman World
I. Nielsen, Thermae et Balneae
F. Yugul, Baths and Bathing in Classical Antiquity
If you have any specific questions do please ask them here! I love this side of Roman history, and would be more than happy to help where I can.