Is there any dark wood in the bathroom? If so, dark wood (wengé). Is there an accent color? If so, there's your shelf color. Otherwise I'd pick satin glass or white.

I have had some experience with 'off the shelf' floating shelves. Beware they can be very flimsy and care must be taken to ensure very little is placed on them. They are really only for display and wont take much weight. Also the brackets often are not very secure. I would advise not to use them to store books or any other heavy items, glass vases etc. Having said that they fill a blank wall very cheaply and smartly.

I've tried several different types of floating shelves and never found them sufficiently robust. They always seem to slope down at the front and I haven't even tried to put anything on them as heavy as a book. It may be that I'm not paying enough for them, I have bought them from the various retailers such as B&Q and homebase. Instead of floating shelves, I now use clamp support brackets which hold the shelf firmly but are more discrete than under-shelf brackets.

It’s a lovely room. I would be wary of floating shelves for books. Could you turn the table the other way and where the image below shows a sideboard have a low wide bookcase? I would also add a round mirror over the top and a table lamp. I can’t see exactly where the downlighters are but hang a pendant over the table to zone that space (or swag the light). I think a rug in front of the sofa will add cosiness and zone that space. Your cushions are nice but in the same fabric, consider swapping a couple for a different texture/pattern. You could also swap 1/2 plants on the tv unit for a table lamp maybe with a pleated or linen shade. I’d probably also add a sheepskin throw on one of the dining benches, the more varied textures you have the cosier it will be especially with lamps (and your books!)