I love Balsamic Vinaigrette (sp?) when we go out somewhere, but also enjoy Italian, and this Greek Vinaigrette I found once. Blue cheese dressing is good for dipping bread in (Rob think's I'm crazy).
I only use Italian. If I go to a restaurant and they don't have it, I'll get 1000 Island; but I only use maybe a teaspoon and mix it in my salad really good.
It totally depends on the salad, and what else it's going with. There are very few bottled dressings that I care for at all. One that's very good, though, is Annie's Naturals Organic Asian Sesame. It's good enough to keep on hand. There are also a couple of Litehouse varieties that we like for certain salads: the Pomegranate and Blueberry and the Raspberry Walnut Vinaigrette. Other than those, I tend not to buy ready-made, and just do something oil and vinegar based that suits the particular salad.