My neighborhood Costco. Regularly quite busy but plenty of parking, so you always find a spot somewhere. You can find great deals on bulk items (though the rawhide I used to get for my dog isn't there anymore). If you get there right when it opens the wait in lines isn't bad. And it can be fairly easy to run in and grab just one or two items, which is what I almost always do.
The member gas station has been our favourite aspect and the main reason we got a membership. We never fill up anywhere else. Generally about 5 cents less than others nearby.