Actually I think you captured her essence very right. Luna is a dreamweaver for all of the ponykind, remember. She shepards and guards the sleep of her little ponies, like Celly guards and steers them in their waking hours. Thus I'd expect she sleeps unusually long hours, but is very active while awake.

I could see this place as the 'prelude' to her chamber, where she spends half of her life. A place of mental transition from one life to another. The colors gradually get darker, softer, the starry floor reminds me of the "dreamspace", without up or down, left or right. It's just – space. I would imagine her bed is also very different from usual pony's bed.

Behind those doors lies an entrance to another world, one she visits every night. The soft place. The realm of weaving. As the colors darken, the space becomes fuzzy and murky, and the edge, separating our realities becomes thin. Just one look down...

Diving in the star-speckled pool...

To find her wings afloat with otherworldly currents.

There, on the other side.