Hello,
In few sentences I will present you this solution:
In order to have natural light in all apartments and breakfast area they are suited around communications- hallways, stairs and lift. Also I left terrace where it was, just one wall is moved right to get enough area of apartment 4.
I don't think that mezzanine is necessary because beauty in such spaces in old town centers is in high ceiling. Here are also some inspirational photos how this space could be designed after. Main focus could be on ceiling height and lighting interesting pendant lamps, false ceiling with hidden lights, boiserie or simple fretwork on the rooms’ walls. Also color preposition is in inspirational photos.
Best regards,
Sanja