To some degree, it's personal preference, and sometimes, it just depends on how the house ends up. I can see benefits to both. I've never lived in a closet-first house, and I've lived in two bath-first houses. The production home I'm building now also has a bath-first arrangement. I like the idea of not needing to pass through the bathroom when I'm putting away laundry, but I also like the idea of a closer toilet (my husband gets up in the middle of the night). I am in the habit of gathering my clothing *prior* to showering, whereas my husband likes the closet adjacent to the shower so he can go get his clothes afterward. We also like the idea of connecting the closet to the laundry room, and then connecting the laundry to the kids' bathroom (via a door or a pass-through), which requires a [master bed --> master bath --> master closet --> laundry --> kids' hall bath] sequence. I also strongly prefer all bedrooms on the same wing/side of the house. Honestly, I could live happily either way... The houses I grew up in never had a master suite, so I feel lucky to have it. :-)

Here are 2 alternate plans I came up with. The first is a wet room concept. I just saw something like this at an open house. I could put between pane blinds on the back windows in case we needed privacy some time. The second is only better in the sense that the original shower is almost 5' wide with the outside wall, and the sauna/toilet could be a bit less than 4' wide. So there's a foot of extra space in the middle. (Of course the shower could be cut back a little in width, but not sure how much below 4' I'd want to go.)

Thank you everyone, so helpful to get quick feedback! Nixed the current layout and appreciate the consensus that a separate tub/ shower probably won't work in the current space. I'm almost ready to give up on the tub, trying one more time with your feedback :) Jan - your idea sounds so luxurious, wish I could but we need the office & can't take incorporate the kids bathroom at this time. Jean - I'm intrigued by your layout suggestion, and used it to come up with this one. Could this work? I can re-purpose the existing vanity with this layout, everyone please let me know how/ why this might be a good or bad idea...

Edit 2: In the 2nd pic, the 3rd idea about putting an office nook in place of the current closet would be similar to this: https://www.houzz.com/hznb/photos/my-houzz-1896-victorian-home-gets-a-contemporary-lift-eclectic-home-office-san-francisco-phvw-vp~20898749