Well, I'm pretty sure you have to pay the annual fee and in that case you might as well keep it for the full year.

For many years, I spread my lodging out averaging 40/40/40 at Marriott, Hilton and SPG. My MR balance steadily climbed from 400k to 1MM points and was never upgraded to Gold. Then I consolidated and got PLT. So don't count on any up bumps.