Marriott offers domestic partner benefits to their associates and is generally recognized to be a "gay-friendly" company. Who cares if the CEO supported prop 8? He is a private citizen, and his private life shouldn't matter. It's what he does in public and what he does with his company (which is give domestic partner benefits, has diversity training, a 100% score with HRC, etc.) that should matter.
Boycotting Marriott because the CEO gave personal $$ to support prop 8 would be like your boss firing you because you gave personal $$ to Obama. It just doesn't make sense.
My $$ will be staying at Marriott regardless of the CEO's personal stand on the issue.