I am going to try and help. You fine gentlemen have helped me so much. I always tell myself I am going to write a review. I even note what time I arrive and time intervals and activities and have never written a damned review. Since this is near and dear to my heart, here are the places I can remember off the top of my head where I have gotten a TS in the past year.
You are correct, nobody fucking offers it. I always ask if they have one the first time I go and request to get one prior to the massage. Be warned, when they are not aware how to do it, they can be; very mechanical, unclean, super hot/super cold and occasionally you get jerked off with conditioner.
Go see Lyly at New Spa on Tomball Parkway. She'll give you a bodyside table shower and if you're lucky (YMMV), get the fun and games on the table shower as well