Aloha,
In addition to the extra 5% Marriott-point bonus, Platinum members get the (in)famous "Platinum box" -- a box full of sometimes expired snacks and 2 water bottles. It's nothing to get all excited about. In addition, we can always get a room, even at sold-out hotels, if requested 48 hours in advance and willing to pay a fairly high rate.
It's really not such a big deal to be Platinum, compared to Gold, but on the other hand, many people who reach 50 nights reach 75. It's not a big stretch. This year I'll have 71 nights, and ordinarily I would make sure to get another 4, but like most Platinum members, my status doesn't expire until 1/31/2002, so I don't need to!
Bruce