On the main I agree with everything that's already been said - having friendly, helpful, knowledgeable and non-judgmental staff is key!
I also need a shop that stays open late at least a couple times a week; I'm SO fortunate that my favorite LQS is right across the street from my office, but many working folks would never have a chance to get there because they close at five. (All the LQSs in town do. Boo.)
Good fabric organization and steady turnover in the FQ bin are also helpful.
I LOVE walking into the shop to see one of the women working on a quilt! The owner and salespersons in my LQS all quilt, and when they aren't busy helping customers they're working on their own projects, or on things for other clients. It is so great to be cared for by someone who just stood up from a sewing machine. :)