I always OC at Topsy Wal-Mart, at least once a week. Don't like being there that much, but it's close. I have also talked to the store PM Manager about it. They are fully aware of OC'ers and so is their surveillance and security staff. They don't mind and were very nice.
My wife also OC's in their too. Both of us have been OCing their for past 3-4 months.
Other place's we've OC'ed at: Petco, BestBuy, Home Depot, Lowes, 7-11 on College, Borders on Topsy, Starbucks on Topsy of course, China Jade Horse Restaurant on Topsy Ln., and Quiznos on Topsy Ln.
Even went into someone's house when looking for a dog from Craigslist, they just stared and were nice, just like good ole law abiding Americans are to one another!
Have fun!