Ok, several years of 5 nights of suite upgrade, and I'm still at 0%. They always say "Sorry, we couldn't use your upgrade ...."
I've been "upgraded" a few times, NOT using the Suite Night thing. ONE was totally useless, as it was an airport hotel for a early flight and I was literally in the room about 7 hours total. Didn't even SEE that they gave me a two room suite!
They DID upgrade me, I guess, one time when I had some family with me, which was nice.
BUT, I have tried the upgrades about 5 or 6 times when I wanted / needed the upgrade ... 0 for 5 or 6 on the requests