They are awesome - knowledgeable, friendly, won't "lie" if they don't have the answers...and have excellent prices. Since I live 40 min away, I have had the pleasure of knowing them personally and you truly will be pleased doing business with them.
Another good site is http://www.exoticfish.com. I work a block away and spend just about every lunch break hanging out talking to Jeff. They have some of the nicest corals I have ever seen at a shop like this. And their prices are not bad. If any of you live in the Los Angeles area, you can join The Marine Aquarium Society of Los Angeles County and get 10% off anything they have. http://www.maslac.org/
We have had good luck with etropicals.com. I believe they are now owned by drsfostersmith.com (another good retailer). I also agree with Premium Aquatics, Marine Depot, and Reef Fanatic. I have had good experiences with all of the above. Another one that we order from regularly is Flying Fish Express (ffexpress.com).