Remaining: one 5" hole (valve) and one 1" hole (shower head). I have all of the rest of the tile up, just need to cut the holes. Thinkin my only option is local flooring company. Anything I can use to cut it myself?

Spade bit intended for ceramic/concrete. Drill very slow.

Diamond bit hole saw, or glass spade bit and do several holes, but marble is brittle and likes to crack along the veins. The showers I have done, I always tried to lay out the pattern so there would be a grout line where the showerhead and valves fell, so I could just V notch the tiles. But that probably won't help you now.

I laid it out so the shower head is at a grout line, but I couldn't on the valve without it looking completely awkward. Well, maybe I could have, but for that one, it is too late.

Got a local tile installer coming tomorrow. Says he uses a grinder with a ceramic blade. I know there are diamond-tipped hole saws, but they cost a fortune for a one-time use tool. Kinda worried about the use of a grinder, but I have some overage, so if he can't get it done well, I won't be any worse off for it.

I would not worry; the professionals make those cuts in 30 seconds that we do in 3 hours!

Wow! 4" grinder with diamond wheel...put that one in your toolbox. Cut it with ease...