I think the nights requirement is the most strict. You have to either travel a lot for many years or live at a Marriott for 3-5 years in order to reach it. I have not called recently for my lifetime total, but I have earned a bit over a million points earned on about 327 nights (with 30 of those nights from the Premier card). I still have another 6.5 years to go before reaching 12 years with Marriott. Lifetime gold should happen for me based on expected travel for the next few years, but I will not get lifetime platinum in 2014 unless I keep traveling at my current rate for another 5-6 years.