I would post a photo of the trim set I bought, but the only one I have is from the California Faucets website. I'm not sure that's kosher since I don't own the rights...but it's a standard three-handle setup with cross handles.

I'm really hoping I won't have to switch to a single handle jobby. Anyone know if thermostatic valves can be used with three handle sets?

Here is a link that might be useful: California Faucets Doheny Three-Handle Trim

You can have two handles (three if one is to select water outlet), although rather than one knob each for hot and cold, you'll have one for volume and one for temperature. Set the temperature that you like, then turn on the volume knob to select full or partial water flow. The valve will react on its own as hot water from the distant tank reaches the shower and automatically compensate by adding cooler water as needed in order to hold your set temperature. (clear?)

Sometimes the temperature and volume knobs are shaped identically; sometimes the volume knob has a larger lever (since it gets moved more often).

Your local codes may be satisfied with just a pressure-balanced valve (that avoids scalding due to someone choking the cold water supply when flushing a toilet, etc.)., less expensive but less desirable since you'll need to fiddle with the temperature knob more often since the water temp will change with the seasons, and it will take longer for hot water to reach your shower if you don't manipulate the knobs for this purpose.

Try this hit.

You'll have difficulty finding a 3-handled thermostatic or pressure-balanced valve, because independent control (separate hot and cold water valves) of the temperature is sort of counter-intuitive to what anti-scald protection is all about.

I have to fess and say I'm not familiar with the efficacy of the valve that I linked to, or how, aesthetically, it will appear on the wall.

Mongo

Thanks, lee676 and Mongo. I'll check out the valve you linked to, Mongo, and run it by my plumber. You answered the question I had, too -- thanks for the information. If the city requires anti-scald protection, I guess it looks like I'll be replacing my bath faucet.