I can't speak about each of the 1100 odd Marriott hotels inside the STARS and Luminous program, but in terms of Edition lots of properties are doing 3 for 2 as you mentioned which brings the rate point lower to any AAA or pre-paid offer.
However, generally speaking yes if you are willing to work with pre-paid rates and those payment terms then you might win on the price side of things, but not always on the value
A professional advisor can still book you a pre-paid rate at an Edition property

If you want to talk big picture, let's go off this thread about perks at Edition properties