As you say you're quite new to Bonvoy, I'm surprised nobody else has already raised a red flag to you about the randomness and unreliability of NUAs as a way of securing the actual room or suite you want to stay in. Plenty of people do as you do and do paid stays at branded hotels, Marriott brands in your case, to accrue points for vacation rooms that they would otherwise be reluctant to pay cash for however the use of Bonvoy NUAs should only be viewed as icing on the cake in the event they are granted rather than the cake itself and it's best you know this from the outset so you do not think that you can plan ahead and use them to secure the upgraded room you actually want in a bucket list hotel in advance. There's a whole thread on NUAs and the SNAs that preceded them in this forum and you should familiarise yourself with the legion of tales of woe and despair that populate it.

On the other hand, you'll also find some random anecdotes of fantastic upgrades to presidential suites retailing at many thousands of USDs a few days before check-in. Accepting the randomness and appreciating the occasions they do provide surprising value is part of the rustic charm of NUAs. Just don't rely on - or plan with - them for anything. Many of us, including myself this year, end the year with a full set of expiring NUAs having been unable to redeem them or end up blowing them on an "upgraded" room on a higher floor on a throwaway reservation in December for the sake of it.