Do you have grand-kids, or are you expecting any near your guest bedrooms? If so, do consider having tubs (at least a small 5 foot inexpensive one) for baths. You won't regret that, especially for resale. As for your Master Bath, ask a realtor friend and they will likely tell you it's 'best' for re-sale for a 5-piece Master too, but if you'd much rather have the extra-large shower than a smaller shower and tub, then go for the larger shower and forget the tub. We have an oversized shower (dual heads, etc) and absolutely love it. We have a big jacuzzi tub too and it's nice but doesn't get a whole lot of use. Our overall bathroom is quite large, but if I were limited on space, the tub would be the first to go or at least downsize. As you age, you will probably find a better use for a walk-in shower with things you can add in your later remodel (hand-held rails, bench, etc) than a tub that is hard to step into.

That alcove is designed to house a tub only, not a tub shower unit. You can't "repurpose" what's there without water damage to your floor, window, and behind your walls. The tub itself not designed to be used that way, and neither is the window designed to be in a wet area. You'd need to rip it all out and start over by installing a smaller and waterproof window, then installing a tub that had an integral tile flange which is part of the waterproofing system needed. Then your waterproofing membrane and whatever wall cladding you might want.

Not sure what the T would be for. Every one i've installed it was a straight run from the top of the valve to the shower head. The valve should have two outlets, one for the shower, the other for the tub spout.HTH

cwalen, we're in a converted industrial warehouse building with concrete floors, so we didn't have much choice --- we had to build the floor up a little so the drain (we used a linear drain, which needs less buildup than a regular drain) wouldn't stick up. Then we built a curb which is tiled. We have not done a door at all yet -- just a shower curtain. I like the curtain, it looks great and it's easy to clean. No leaking as long as the curtain is closed. I don't seem to have a decent picture on my computer, but if you need pix, I'd be happy to take some tonight.