As a Platinum, that has never happened to me. Then again, in the last 3 years as Platinum I have received 2 upgrades to a suite. When I check in I ask for a corner room which tend to be bigger than the average.

Personally, I would not pay $150 for a suite upgrade. But if you feel that you really need the extra space then you will have to consider it. Have you checked to see the rate of a suite booked on marriott.com compared to the $300 offered by the hotel?

You might want to call The Platinum Service desk and ask if they could contact the hotel to try it's best for a larger room. Even if they document the REZ that might help when you check-in.

That should be a busy weekend, arrive early and hope for the best. Good Luck