Very clearly defined model. Good start. The compositional duality expressed in black and white is very helpful for reviewers, and will be very useful to you as you develop your concept.
The relationships, however, are so exclusive that I wonder whether you'll be able to wring much compositional or experiential meaning from it. If the program elements can be arranged to more obviously support each other or interrelate on some levels, the form and meaning can be more complex and more interesting to develop. 
Here's a thought: Why not wrap the spa garden with the hotel? Or imagine carving the spa from the center of a hotel mass; in effect using the hotel functions as a thick wall to protect the spa. 
The perforations you've suggested in the spa wall might be developed into openings that penetrate the hotel in strategic ways, linking spa, hotel and context. 
Also, I think that economic logic suggests the hotel should be bigger than the spa. Room rates drive revenues and supply the spa with customers, so extending it round the site perimeter would expand the area for rooms. 
Thanks for the post.