I agree with VA1379 that the time to address the issues is while you are still on-site. There's no way for them to satisfy you as a customer once you've left the property, unless you are looking for points (and you say that you aren't).

We've had a number of Marriott stays where the service has been unsatifactory (water was out for 2 days, room issues, safety issues just to name a few) and every time we've addressed it on-site, it has been fixed, either with a step-up in service or a personal visit/call from the GM , a fruit plate or a credit.

On the occasions where we've waited til we returned home, we've also received the generic "sorry about your recent troubles" email. Receiving a letter like that is why we'll never stay at the Renaissance Las Vegas EVER again. Their choice, our choice. Once you leave, your only recourse is to never give that location another dollar. Probably more inconvenient for us than for the hotel. So yes, best to address it when it happens.