All of the above is nice, but you've missed the single biggest benefit - waitlist priority. At least a couple of times a year I find myself in DFW or IAD or MIA with snow at my homebase (ORD). The early flights are all cancelled, last flight of the day has a waiting list as long as your arm; the babies are crying, the oldsters are whining. Up to the counter, out with the 1K card, "window or aisle, sir?".

I also get a couple of hundred dollar discount on a family RCC membership; no matter what you decide ALWAYS join your airlines club. All it takes is one delay when the line is out the door at the regular counter to pay for the membership in terms of aggravation avoided.