Waterfall shower and bath - I'd add a divider that goes up and down at the push of a button so it keeps pool and shower/bath water separate and drain out. After shower/bath, the dividers go down and the area fils up to extend the pool.
Love the Japanese idea of a window flush with the tub! Nothing says relaxation like a nice soak with the breeze :) (There'd need to be a tree or something though for privacy haha) . there is a Japanese Garden (patio) outside.