I've ordered from three retailers so far. Anchorage is currently down to one locally owned LFS (which rocks btw) and two petcos. I try to buy my stuff from the LFS whenever I can, but some things are just too expensive and/or unavailable.
My most recent purchase was through blue zoo aquatics; a yellow tang and some blue zoanthids. The packing was excellent, although the zoanthids were out of water (bag broke?) and the tang was much larger than I ordered. (Ordered a 'tiny' tang, 1-1.5", and the one that arrived is 3"). However, he's in excellent health, very vivid yellow and flawless fins. The zoanthids came with a anemone looking hitchhiker, haven't gotten a good glimpse of it yet but I don't think it's a pest.
I also ordered a clean up crew from reefcleaners.org, and was very impressed. I can't recommend them highly enough, they have the best snails for the money, hands down. And they ship priority mail (I live in Alaska, and despite the few days in a shipping bag, 99% of the snails made the trip perfectly fine).
My experience with my Diver's Den stuff wasn't pleasant. I lost an entire colony of pink ray zoanthids, and the box I received was beat up, probably thrown around by the guys at UPS. The shipping bag was cloudy and filled with debris. I can't say any of this is the Diver's Den fault, I didn't do their live arrival guarantee because everything was alive, it just melted away. I kept holding on to the hope that some of the zoanthids would pull through, but despite coral dips and trying different locations in the tank, they vanished over the course of a couple weeks. There were some green zoanthids on the same rock that are thriving just fine, so I don't know why the pink ones melted away. However, the pink rays is what I bought the rock for, otherwise it was $188 down the drain. The rock also had several small aiptasia on it.
Anyway, I'd rather buy from the LFS so I can see first hand what I'm getting, but WYSIWYG is awesome as well, especially when I can't find many of the prettier corals here. :Cheers: