I can see where Bill's coming from, because I use the same criterion very heavily. For all the discussion in this thread about quality, Star Trek's primary utility to me is entertainment, not whether it is an artistic or critic-friendly statement. Of course, there can be overlap, but many times it doesn't necessarily follow. The most useful way for me to judge a TNG episode is not "is it good?" but "do I enjoy it?". So rewatchability is going to be a major part of the way I personally rate episodes. I think this comes through quite strongly in my picks in that Top20 of TNG thread that popped up fairly recently. Lots of my choices don't tend to be critical highlights, but I enjoy them the most. For an entertainment series, I think that's crucial.