Good people - Everything else comes naturally after that!
The most important thing I look for at dive shops is knowledgable, respectful, well trained sales staff.
staff who loves to dive themself.
Thanks guys, those are great points. I guess what I'm looking for though, are physical things. What would the pool be like, what would the layout of the store include, etc.
It is about the staff first. Amenities can make a difference but pale if the staff has a bad or dismissive attitude just as any shop accessory missing can be compensated by a friendly and caring staff.
That said, your hard features I'd like.
Compressor
The ability to do tank hydros, maintenance and inspections.
Nitrox
Access to a diving pool, nearby or onsite.
Air conditioned fitting rooms.
A wide variety of inventory.
An active dive club.