So, last year in 2011 I had 62 nights. Marriott Rewards rolled over 12 so that was my base in 2012. Now I'm at 73 nights and can easily get to 75, but I wonder if they will give me platinum and roll over 25 nights (above the 50 to be gold) or if I just become platinum and nothing rolls over? I see very little extra value between gold and platinum and would likely choose to hold my nights below 75 if I'll get that big rollover by staying at Gold.
To me there is a difference between Platinum and Gold. We get the platinum gift, a 50% bonus on points earned which could add up and I would assume that we would get priority if any upgrades are given. You sound like to travel a fair amount and is that 11 nt rollover going to make that much of a difference?
My guess: if you leave yourself at 73 nights you will be upgraded to Platinum anyhow. Then you will receive whatever nights you have earned in excess of Platinum as rollover -- in other words, for you, zero. (And true, even if you stay at 73 and somehow you are not awarded Platinum (unlikely, in my opinion) the 12 already rolled over from 2011 won't count again so only 11 will roll over.)