American Express Membership Rewards - certs for travel vs others.

I see I can claim 10k points for use against car rentals at $100 value or other travel using certs rather than having points converted. I want to do a 3 month AVIS car rental. However the variable is the rate that AMEX's Travel centre can get.

I know I can get a better rate so my question is how do I get the same rate through AMEX Travel rather than the lazy rates they will get for me??? I simply do not want to burn points on their losy deals.

When I've booked through PLT travel services the daily rates the quote me sound high BUT the quote an average price per day rather than X weekdays @$ and X weekend days @$. When I compare that to a quote from the car rental people directly they usually end up very very close. I don't use priceline type bookings so I don't know that comparision.

I would personally use the certificates when renting a car during high dollar times when there are NO good deals. We like to use them when we are renting a 4WD suv from Denver at spring break or Christmas. Rates are sickening then so the certificates help!