501 is pretty good for deer, but not so good for elk. 550 is probably a better elk unit than a deer unit. Not saying there aren't both species in both units, but I would decide what you really want to hunt and concentrate on that species. Both units get LOTS of hunting pressure. But either one would be just as good or better than any of the others that are open. So you're on the right track. I can't comment on 633 as I've never hunted it.