The vertical wall seams crack more readily because the house shifts and moves. Ive tried grouting only and going back to caulk with sanded grout caulk or silicon only after a crack develops, hoping in some cases it will not. Sometimes it does not crack. Some contractors caulk all seams as a matter of course, no callbacks, safer. I liked the idea of sanded grout caulk to match your grout color It has not held up for me in wet conditions, such as the top of the bathtub where the wall tile starts, etc. , definitely not along the shower floor where the wall tile starts. It has held up in other areas though, and looks nicer when it all ties in. I agree, mildew on silicon is unsightly. Every bathroom has different conditions, including ventilation, moisture, etc. Some people have to clean out and recaulk the silicon every year or two. Whether its allegedly mildewproof silicon or not.

We hired a GC to remodel our kitchen, powder, laundry and two baths. His workers do the plumbing, electrical, drywall and tile work, he doesn't sub it out, so that is a cost savings. We talked about the vanity this morning and he said the tile on the side would go on thinset, not the full-on thick mortar like the floor or the wall (it doesn't have to "float"). My problem is we were originally going to put the 4" backsplash where the vanity and tub meet but now might have to do a full tile piece due to the overall tile design. The granite countertop has been cut already, not installed though, and I'm not convinced the tile could fit in the lip between the granite and side of the vanity. Plus, different stone tile sizes have different thicknesses, I will have to make sure it fits underneath. You're right, there are a lot of little things to think of.

That gap is supposed to be there to accommodate for expansion/contraction of the different materials. Tile is intended to bridge the gap. Honestly in my opinion you're much better off that your GC didn't install 'waterproofing' behind the cement board. The notion of putting poly behind the cement board by stapling it to the studs and then peppering it with screws through the cement board as a waterproofing technique is ridiculous. Cement board is porous, grout is porous. Water will go through the grout, through the cement board, through the poly (or worse accumulate between the cement board and poly) and rot the cement board. It is NOT water proof - it will hold up better than drywall when wet, but not forever or for the long term. You also don't want a 'water sandwich' i.e. poly behind the cement board and then waterproofing on top of the cement board as this just completely traps any moisture in that envelope. That's a basic tenant of all vapor barrier installations. If it were my bathroom, I'd be installing a waterproofing membrane like Kerdi on top of the cement board. It would extend to the top edge of the tub covering that gap. Tile then gets installed all the way to the edge of the tub. Grout goes everywhere except along the bottom edge of the tile where it meets the tub - there you put silicone caulking to allow for the movement of the tub without cracking the grout. The tub will move/flex/expand/contract.

I"m short on time, but wanted to post something that's been swirling in my brain. I think walk in closets are lovely if you have the space, but I just don't think you have the space; I'm pretty confident that the minimum recommended width of a closet is 5'. How about a walk- through closet to your bathroom? My guesstimate is that you could have 6' wide, reach in closets on either side of a 42" hallway. I've seen lots of pictures with a beautiful tub centered under a window and flanked by vanities, so I appreciate that look might be a priority to you. I just moved all that over to the other window. I tucked the toilet and shower around the corner. Depending on the location of the window, you might be able to have a pocket door, but if not, a wall would add a lot of privacy (avoid seeing the reflection of someone on the toilet from the entrance or the rest of the bathroom.) Anyhoo. Here's a rough drawing. If aging in place is a concern, I'd put the shower and toilet on the exterior or bedroom wall, so you have the option of creating a quicker route to the toilet (through the closet wall) in the future.