The link to the Costco warmer seems to be broken (at least it didn't work for me). I have included a link to the Ancona Comfort 8. Price $229.99 Features (cut and pasted): Freestanding or wall hung towel warmer and drying rack that can be located in your bathroom, laundry room or other convenient areas Carbon steel construction with Chrome finish Sleek Mediterranean styling All parts and instructions included Reaches its preset ideal temperature in 15 minutes Engineered with dry-lined electric power to be safe and energy efficient, so it can remain on for convenient daily use 110 volts, 150 Watts, with on/off switch; cUL certified Dimensions: 37" (93 cm) height; 24" (60 cm) width; depth 12" (30 cm) Weight: 11 Lbs (5.0 KG) 1 year limited warranty Costco also has the Comfort 9S, currently priced $199.99 (after instant rebate). Features (cut and pasted): Features: 304 Grade Stainless Steel Towel warmer and drying rack that is wall mounted Sleek Mediterranean styling All parts and instructions included 6 feet (1,8m) power chord to plug into a standard grounded 3-pin electrical outlet Reaches its preset ideal temperature in 15 minutes Engineered with dry-lined electric power to be safe and energy efficient, so it can remain on for convenient daily use 110 volts, 150 Watts, with on/off switch, UL certified Dimensions: 30" (76 cm) height; 24" (60 cm) width Weight: 11 Lbs (5.0 KG) 1 year limited warranty Here is a link that might be useful: Ancona Comfort 8

Since you don't want to heat the room with the towel warmer, I'd be more concerned about the average temperature that the unit gets, whether it has a programmable timer and maybe even a temperature control so that you have the towel toasty warm when and how hot you want. I don't know about curved bars; you bring up a good point. I do know that the more layers you can create on the warmer, the more insulation you provide for the towel to stay warm. So, you're right about the number of bars so more surface area touches the towel as well as making the towel thick as you put it on the bar. Hope that makes sense. Here's a towel warmer that looks like it meets most of your needs. Good luck with your project! Here is a link that might be useful: Towel Warmer that meets your needs

Home Depot has a large selection, many with consumers' anecdotal reviews.

This is a lot of information without seeing a floorplan or photos. The Kohler Underscore tub is a good one; I just put in a tub/shower in a client's guest bath using that model with a glass slider door. If there's room for a separate shower, you could do a configuration in which the undermount tub deck extends into the adjacent shower to form a bench. Like this: Or this: As for the heating, check with your contractor to find out how difficult it would be to move the ducting to the floor or the adjacent wall near the floor. I'm betting it's not that difficult or expensive. As for 72" vanities, those are going to be pretty expensive no matter how you slice it. Take a look at Pottery Barn and/or Waterworks.