I've only been checking out Costco wine for a few months, but so far I was not so impressed.  I know they are the biggest vendors in the world and are also the biggest vendors of Bordeaux first growths in the US, but their selections seems awkward to me.  Lots of bulkish, mainstream quaffers and some top flight CA and French bottlings,  but not much in the middle, not much for the discerning wine drinker who doesn't have a large budget.  Not much either, for the adventurous wine drinker...but I know that's too much to expect from a big box operation.  But yesterday, it was like I entered a different store...tons of mid-range, interesting wines.  Also at least 12 different Spanish wines....some typical picks, some awesome picks, some a little strange, but overall a Spanish wine fest!  For the first time I had to force myself to stop picking out bottles.....