Steamshowers, you mentioned Kerdi, when I do Kerdi it's over cement board. Not Hardie. Durock is my first choice, Wonderboard my second. You'll need to Kerdi all six sides of the shower cube. Ceiling too. And you'll want to gasket the shower valve hole and the shower arm hole with Kerdi so moisture doesn't escape into the wall from those openings. You mentioned recessed lights in the shower. Look for "vapor proof" lights. Not just "damp" or "wet" proof. Vapor proof lights are gasketed and sealed to prevent moisture vapor from getting in to the housing and trashing the light from within, or from getting through the ceiling hole and into your framing bays. They can be expensive. Speakers within the shower. Same thing. They have to be able to withstand the steam environment. Ventilation, the same. Some put a "standard" vent outside the shower just above the shower door to keep things simple. Music? If you don't already have a set-up, look in to Sonos. It's my whole-house (and outside in my yard) music system. I love it. You can gradually expand it to other parts of you house should you desire. And there's an app for your android. I recommend porcelain tile in the steamer. Leave natural stone out due to moisture issues. Steam condensation can drip down on steam users. Some slope the ceiling to help avoid that. Grout lines can act as drip points. Just something to be aware of if you're not already. Good luck!

Nice job! Being on the last leg of the reno of the 3rd (and last) bathroom in my house, I can appreciate that sometimes there are things that do not get the attention they should have initially. Like not noticing that the old toilet was centered 16 in from the wall and to remedy that the sick had to move which meant that the door wouldn't close etc etc etc. However, having looked at your pics and consulted with my project manager, we thought that you could look for something to put where you have the little freebee. It could be a one piece unit or a base either cupboard or drawers and a top that matched style wise. You could even place the little one you have on top, with or without the legs. Paint it whatever colour suits you. You could even hang the little one over the toilet tank ( too crowded for me ) or on the adjacent wall , if it didn't interfere with the toilet. In any event, I think the space between the windows is perfect as long as its clean , neat and eyepleasing as I infere from the pics that that is the first thing you are going to see when you enter. IT's amazing what a non-descript bureau or cupboard can look like with a couple of coats of melamine paint ! The Boss offered the suggestion that if you need storage for hair products, portable hair dryer etc, after years of struggling with cupboard storage, mess, things falling over, etc, she finally started using a large basket that she keeps in the closet in the adjoining room ( sometimes ) . Everything is close to hand, easily portable and actually doesn't look bad if left out . Good luck with the rest of the transformation

Revelation---I don't think there is a water pipe in the way. I looked after contractor left yesterday and it looks like supply lines are lower in the wall ( the whole wall is not gutted, just the lower part). I have this kohler cabinet in the garage, which I ordered awhile ago but had planned to teturn, and since I also just realized my ceilings upstairs are only 7.5 feet tall, I actually think the IKEA cabinet is too large for my space. So I am going to forevo the IKEA cabinet and attempt to return it assembled. Assumkng he can actually recess this cabinet it will give me a lot more leeway to choose a light fixture, though I still may go for that uber cool tech lighting one!

If you go to your local tile showroom I'm sure they will help you pick all the materials and recommend the right sizes etc. As far as visualizing it all, the most simple way without getting any crazy software, is to use power point. I make visual boards all the time on Power point by just cutting and pasting the items I'm using. You can format the pictures to remove the background and at least get a sense of all the finishes together. This one is super simple, but allowed me to see the wainscoting, flooring and wallpaper.