After having been to a couple restaurants where they have a "house" ranch dressing.. one that is thick and creamy, extremely flavorful, etc. I just can't stomach the store bought stuff anymore. I know I could go google ranch recipe, but I would rather refer to my compadres here. If I had to guess on the base for the ones I've really enjoyed, it would seem to have buttermilk and something like sour cream to thicken it? I don't know if it really had buttermilk.. you might get a similar result with sour cream and heavy cream.
If one of you has a rock-star recipe that matches what I'm after I promise to never, ever buy the nasty store bought abominations again!