As many have stated, friendly staff. (Grouchy seems to be the norm!!). Probably more expensive upfront, but having the latest fabrics,books and patterns keeps me coming back. (Discount stores like JoAnn, have books that have been out for 2+ yrs.)
I personally like ambience (I know its shallow!) but some shops have things like a fireplace, or comfortable area to browse thru books or for husbands to relax in.
Good size cutting area where you can stack up bolts that you want cut.
A knowledgeable staff that can help pick color palettes or determine amounts of fabric needed for a project.
Good luck with your new endeavor!!