Usually in ceilings are used in commercial tenant spaces. But... I've been to many stores and pubs where wall mounted bookshelves were used with fantastic results. As for stereo vs mono, usually all speakers are ran in mono so panning across the room doesnt become an annoying distraction.
Sounds like a really cool doctors office! A not so boring waiting room.
Going to 8" drivers makes a great impact on the system oomph from my limited install and testing experience.