I got a status challenge from Marriott, I knocked out the required nights in a month or so. My Platinum would expire sometime next year if I did nothing about it, but as of now I only need another 19 nights, which I should have by mid-November
I don't consider I have any particular loyalty to either brand. Why would I? I'm the customer.
But I like the perks the top level gives me, I've used both Diamond Force and Platinum before, a real lifesaver when you need it.
I often stay out in the sticks, and Marriott and/or Hilton have by far the best coverage for those small towns.
But I also see the value in having a lot of points with one or the other just so you can spend a fortnight at the JW ski-lodge or whathaveyou.