Because your slab is suspended above a basement, you could float a plywood subfloor or adhere a subfloor to the slab. When we float a subfloor, it is usually two 1/2" or 5/8" plywood layers installed on a diagonal layout to the room with each layer staggered so no seams line up. The layers are attached to each other only. The plywood needs to be dry and reasonably flat. Garbage sheathing will not suffice. Since yours is such a large space, I would suggest you do a lot of research on different install options and consult with installers who have done solid over concrete slabs. One important thing to note is the fact that even though your slab is suspended construction does not mean it is entirely safe to assume it is dry enough to install wood flooring over without providing for some sort of moisture barrier or retarder. Concrete can take up moisture and emit moisture depending upon the temperature and moisture vapor content in surrounding air at any given time period. There have been remarkable advancements in adhesive technology with some adhesive manufacturers making the claim that now you can install a solid to concrete directly when using their product designed to do just that. I have not done that. Engineered wood flooring construction is basically a quality plywood with a veneer face that is the specie of choice. The veneers differ from product to product; some have a thin peeled veneer and others have a sliced (sawn) veneer. The unfinished Owens engineered is of the sawn type with a veneer that is almost a full 1/4" thick. I did an Owens unfinished over sheet cork over a slab where the product married to an existing 3/4" solid wood floor attached over a portion of the house that had a basement. You could not tell the solid from the engineered. Good luck with your searches.

The windows in your wonderful room do present a challenge. I don't know how willing you are to lose one, but here is what I would do. I would look for deeper bedding - I agree that your bedding is too light - you need a richer color to transition between the pale walls and floor and the deep furniture. Not sure of the real wall color, since monitors and light can be deceiving, but perhaps something like this from JC Penney, called aqua blossom. Take your bed and put it up against the end wall, in front of the single window. Then take drapery that matches the bedding and hang that off wood rods in the color of the case goods behind it, closed, to create an elegant fabric backdrop for the bed. I would hang the rod pretty high, to make use of the soaring feeling of the room. Put your nightstands on either side, and add lamps. I would probably do wall-mount swing arms to give more height to balance the headboard. Do the same drapery treatment on the triple window, but just panels hung on either side, and then change out the blinds to wood or woven woods in a richer color. I would create a sitting area in front of the triple windows, with two comfortable upholstered chairs and a shared ottoman, done in a subtle patterned chenille or other soft fabric, in a coral/rust taken from the florals in the bedding. Table between the chairs, with a nice tall lamp. Do the same darker blinds on the dormer windows, and then add the matching valance there, no panels. I would build out window seats with bookshelves underneath in the dormers. I would move the TV to a either a closed armoire type of situation, or wall mount it and put a beautiful console below for other electronics and storage. Place that on the left side of the entry door, to balance the dresser and mirror on the right. It will be visible from the bed and from the seating area. If you can swing the new furniture pieces, I would have the dresser and armoire match the bed - the dresser that is there seems to be a different wood tone. I would use the niche on the wall to put in a fireplace. Not down on the floor level, but up in the niche. It will be visible from the bed that way, as well as from the seating by the window. I would change out the trim to something that matches the darker wood in the room. Something like this, from Magiglo: . Then I would mirror just that one wall area all around the fireplace, to add sparkle and interest to the room. I would take out the ceiling fan and do a pretty chanelier there, add a lamp on the dresser, get rid of the spotlights on the beams or change them to something more subtle. Add some art and you are good to go. Oh, and I think I see dolls up on the beam? They look like they are ready to do a swan...

I like my first idea best as far as use of space. I know people say not to put toilets on an outside wall. We had one in our last house in Iowa, but we had 2X6 construction. I don't know how high your window is, but I'm guessing the toilet would fit under there. The shower would be 5 feet long or shorter if you want a wider space to get to the toilet. (kind of tight the way I have drawn). You could do a 5 and half foot long shower and do an angled door at the left end to allow room between the shower and toilet. The vanity would be about 7 feet long, unless you do a 60 inch vanity with a linen cabinet at the door. I would reverse entry door swing if you do that.. The second top right could work and you would still have a small closet. The bottom left plan would require waterproofing your front window. Hopefully someone will give you other ideas. The bottom right plan is bigger, but no closet. Each square equals 1 foot.

R.O. you could do some painting of the walls to mimic that first photo. Or hire someone do to that framed trim. It would really add some drama to the room. You said warm colors but what about a neutral cool? I am not sure your budget but if you check out places like Homegoods you might find some really gorgeous drapes and hardware. Hang them as high as you can. After you find drapes you like, find a matching color or similar color for your walls. I saw those side table lamps and the exact bench in Homegoods yesterday. ANd of course Wayfair tufted bench round chandelier