(Wasn't sure if discussion was the way to share - but FYI).
I had never received the choice of benefits upon reaching the higher tier in Marriott. Well in 2018 I reached both the ability to choose Suite Night Award and got to select a free night. I tried to read as much as I could on the Insiders information regarding how to go about using SNA, etc... I read several people had issues so thought I would post that I was successful in getting a suite.
After researching many the many Marriott/SPG hotels offered in Boston I decided upon The Westin Copley Place because of location and they seemed to have more suites available than other options. At the time I made reservation (booked a traditional room) towards the end of the reservation process I was able to indicate I would like to use my SNA (for 2 nights) which the screen prompted which suites I would like to consider. I chose 3 suite options presented. From the time I made my reservations to just a week before my stay, the price of my traditional room went down which created slight anxiety that somehow in the process I would lose my SNA in rebooking. Spoke with customer service who guided me through the process again so that I could get the lower standard room rate and still apply for my SNA.
One day before arrival I received an email from The Westin saying I was being awarded my SNA. My room at the Westin went from a traditional king to a 1 bedroom executive suite. I was very pleased.
I have 3 SNA available to use before December 31, 2019.
Hope this serves as hope for anyone that has SNA to hear that I was able to use it.