#1 - friendly, knowledgable customer service
also, I like to see a variety of fabrics, not just focusing on a particular style (for instance mainly 1930's & civil war); lots of threads, samples, patterns, gadgets.
music - a variety would be nice. I get sleepy listening to some of the music one local shop plays.
smells - I have allergies, so some smells, especially flowery or perfumy ones have me running for the door. If you must, keep it subtle.
I'd love to see a place have some gadgets out that you can try before you buy. they do get expensive, and sometimes you end up with several that were a waste of money.
Classes & Newsletters are nice.
Evening/Weekend hours - I work full time. Where I shop depends on the time/day I can do so.
Frequent shopper program!