If you could make a pocket door instead of a slider , you could use that entryway space.

I love the general concept of beams and adding beams, but in this space with the ceiling as it is in the drawing, I think adding beams at lower levels makes things too busy architecturally, considering the soffitt and all of the other planes, angles, and openings.

We have that exact sink! And a very small powder room stuck in the 80s. Only difference is our door is on a side wall, and there is no window. We're no where near finished, but just ripping down the pink floral and stripey wall paper has made a huge difference (including revealing the toilet is in fact white, not pale pink). We're going to replace the rather unappealing plastic sink with a tiny ceramic one with new taps, and the old plastic cistern with a new colonial style ceramic one, and new seat (keeping the toilet base as it is in good condition, and classic style). Then new paint, and a good clean and regrout to the floor, new light shade, toilet roll holder, storage in one corner and art.

I think the shelves would be better as there's not this huge room taking up space. What did you end up doing?