There is an unadvertised rule that you can, once only, get "bumped" to Gold or Platinum if you are within 5 nights of the requirement, 45 or 70. Anyone can request it if they're within the 5 night range.

It's best used only if you really need it. Using it up to jump to Platinum when you're going to stay 5 more nights by the end of the year may not seem like such a good idea when, years later, you find out you missed the Platinum level by 1 night and get downgraded to Gold and don't have this 'saving' exception available.

Oh, and I should mention buybacks. If you drop a level, from time to time, MR will send a "buyback" letter. You can keep doing this as often as you like. 35K points for gold, 50K points for platinum. You don't actually need the letter to do the buyback, you only need to have been at that level before.

I have also noticed that if you stay at Gold or Platinum for several years, and suddently don't stay enough nights, that you'll be "courtesy" renewed by the MR computer. For how long the courtesy renewal will last, or what stay frequency triggers it, I haven't found an explanation of that from anyone at MR yet. It certainly isn't something you can request (so far as I have found).