Mike,

It is extremely unlikely that they will grant you Platinum status without the requisite 75 nights. It is also unlikely they would grant you Gold, but you would have a better chance. Marriott has a reputation of being pretty strict when it comes to awarding status to folks. The good news is that when I was Silver one year, after previously having been Black, Gold, and Platinum, they continued to upgrade me to concierge level when it was available, and always provided me access to the lounge if a concierge level room was unavailable.

I would do a few things.

First, I would always request an upgrade and access to the Concierge Lounge upon check-in even if you are only Silver.

Second, you definitely do not need Platinum for access to Concierge Lounge and/or upgrades to the Concierge Level as this is a benefit of Gold elite level, too. Granted the Platinums will be upgraded first and the likelihood of an upgrade is less as a result.

Third, I would call up the MR CS line and ask them how many lifetime MR points and stays you have. If you used to be a regular Marriott Marquis Black Level then you may well have accumulated enough to qualify for lifetime Gold status, or you may be close enough do some stays in order to achieve it. Below are requirements:

Silver Lifetime:

12 years as an MR member
600 nights in a Marriott banded property
1.5 million points

Gold Lifetime:

12 years as an MR member
800 nights in a Marriott branded property
2 million points

Platinum Lifetime:

12 years as an MR member
1000 nights in Marriott branded hotels
3 million points