Here's one approach (FWIW, your two lavatories are too closely spaced to be useful):

Lose the second sink in the main bathroom. You need vanity space and storage more than extraneous plumbing.

The extra-wide hallway between the stairs and what I assume is the master bedroom seems a waste of space, when the bathroom and closets are so cramped.

I am not a fan of "open to below" spaces, and would much rather see that space as a laundry/storage room.