I emailed GM Card this morning and have already gotten a response back on this. Here is the scoop on American Airlines and Marriott:

Marriott:
The GM Card is proud to announce four exciting new hotel offers for our
Cardmembers through Marriott Hotels, Resorts and Suites:
Redeem $25 in GM Card Earnings and pay only $89 for a "Dinner for Two
Award" certificate good towards dinner-for-two at participating
Marriott
Hotels, Resorts & Suites and Renaissance Hotels and Resorts - or
Redeem $50 in GM Card Earnings and pay only $99 for a "Flex Weekend
Award." This certificate is good toward a one-weekend-night stay
including breakfast for two and taxes at select Marriott Hotels,
Resorts
& Suites in the United States - or
Redeem $100 in GM Card Earnings and pay only $179 for a
"Platinum/Select Weekend Award." This certificate is good toward a
one-weekend-night stay including breakfast for two and taxes at select
Marriott Hotels, Resorts & Suites in the 48 contiguous United States,
Canada, and Mexico - or
Redeem $100 in GM Card Earnings and pay only $259 for a "Worldwide
Award." This certificate good toward a one-night stay including
breakfast for two and taxes at any select Marriott Hotels, Resorts &
Suites and Renaissance Hotels and Resorts locations worldwide.
If you would like to obtain general information on participating
Marriott locations or room availability, please call a Marriott
representative at 1 800 228-9290. Once you redeem your GM Card
Earnings,
you will receive a Marriott certificate within 7-10 business days.
Identify you have a certificate when making your reservations and
present your certificate at time of check in. Participating locations
are also listed on the back of each Marriott certificate. Certificates
are non-returnable.
Terms and Conditions:
Some restrictions may apply specific to the offer chosen and the
properties mentioned therein. Hotels for each offer are listed on the
certificates themselves. Weekend nights are defined as Friday,
Saturday,
or Sunday. Prices are subject to change. Once the certificate is
issued,
the certificate is valid through December 31st of the following year.
Certificates are non-returnable. For complete hotel listing for each
offer, call Marriott toll-free at 1 800 228-9290.
Visit the Marriott website for more information.

American Air:
The GM Card is proud to announce a special new airfare offer for our
Cardmembers through American Airlines. Redeem $50 in GM Card Earnings
and receive:
A $25 discount on domestic flights within the 48 contiguous United
States, Mexico, and Hawaii on fares from $150 to $249 - or
A $50 discount on domestic flights within the 48 contiguous United
States, Mexico, and Hawaii on fares from $250 to $349 or on flights to
Europe on fares from $300 to $399 - or
A $75 discount on domestic flights within the 48 contiguous United
States, Mexico, and Hawaii on fares from $350 to $499 or on flights to
Europe on fares from $400 to $499 - or
A $100 discount on domestic flights within the 48 contiguous United
States, Mexico, Hawaii or on flights to Europe on fares $500 and up.
This special offer is good for up to four tickets per reservation.
Once you redeem your GM Card Earnings, you will receive a confirmation
letter within 7-10 business days. This confirmation letter will contain
an authorization code. Provide this authorization code to American
Airlines when making your reservation. If you would like to obtain
general information on American Airlines travel destinations, departure
times, or fare information, please call American Airlines at
1-800-433-1790.
Terms and Conditions:
A 14-day advance purchase is necessary and Saturday night stay is
required. Other restrictions and blackout dates apply. This offer is
good for one reservation of up to four tickets and is non-transferable
and non-returnable. This offer is valid for twelve months from the date
of issue. Offer expires December 31, 2001.
Visit the American Airlines website for more information.