I wouldn't use Whole Foods as my primary "supermarket", but it really is the best for getting meals and food staples. Now, if they would just carry Coke Zero...
I would go to this Whole Food, and not the one down the Strip on LVB. This one has much more selection, a massive wine section and tons of delcious prepared foods for dinners (stuffed chicken, organic meats, etc.).
Make a lunch of this experience at their to-go section (they have seating), get your meal before you shop, and you'll save yourself money. I always buy less after eating.
All aroudn knowledgeable and friendly staff. Prices are high, but expectedly so.