A clean bathroom, cuz I might spend hours at the shop!
Fabulous lighting in all corners of the store - even in the clearance section if there is one.
Consistently friendly staff. Treat ALL customers as though they were important, not just the ones you already know. You never know when a new customer might turn out to be your best customer.
Coffee pot, water cooler. Nothing fancy, just a place to wet your whistle.
A chair or two here and there for the hapless person who might be accompanying the quilter but not interested in shopping. Maybe with a small side table??
A place, or several places in the store where a person can lay bolts of fabric out to audition them - not just on the cutting table at the end of the store. The cutting table, hopefully, will always be full of fabric being cut!
Evening hours once or twice a week for those of us still lucky enough to have day jobs.
Good luck!