Amber Unicorn is a gem in Las Vegas, used bookstore-wise. The couple who owns the place are whip-smart on their stock and very pleasant.
If cookbooks are your weakness (they are mine!) you will be in heaven! But, a small word of warning: Myrna knows her stuff, and prices accordingly. If you've been looking for a 1950's Swedish cookbook IN SWEDISH, she'll have it, and it will -not- be $5 bucks. I've been a bit taken aback by some of her pricing on cookbooks, but many are fair and i'm willing to pay.
A good selection of sci-fi and vampire books are a nice addition that I don't think can be beat in Vegas.
If you are looking for a specific book, call them and see if it's in stock. If it's not at the shop, it may be at their home, and they will bring it in for you.