you could do a few things

1. I am assuming you are not an elite member, you could register for the instant silver status and get 20% bonus on the base points

2. Apply for the Marriott premier visa card (the black one, not the silver visa card) to get 20K bonus points, a cat 1-4 free night cert, 2 for 1 golf cert, 15 nights credit towards elite status and 5 points per $ spent at Marriotts, 2 per $ on air/dine/car and 1 point per $ on rest of the charges. The card has a $65 annual fee but the free night cert itself is worth it.

3. Check this forum for Marriott promotions around August

4. Check if you have any stays that can net you bonus bucks and you could use them to cut down your room rate but still earn points. Geico previleges sold them in the past and may do it again. read the BB T&C if you plan on using them.

5. If any of your stays are weekend stays see if any MEB rate applies.

6. Check the publicly available Marriott codes thread and use the Marriott best rate guarantee if you find any better rate using the codes or on other websites

7.check AAA rates as they vary a lot and few nights on AAA rate could be worth the AAA fee.