Marriott and United have started a promotion that provides 1,000 United miles (up to 10,000) for each stay in a Marriott hotel in the US/Canada/Mexico.
This is the link to register.
You will need to switch your earning preference to United MileagePlus miles in order to activate it
Stay from May 30, 2013 through August 30, 2013 at select JW Marriott,® Autograph Collection® Hotels, Renaissance® Hotels, Marriott Hotels & Resorts®, or Gaylord Hotels® and you will receive 1,000 bonus miles with United MileagePlus. This offer doesn't last forever, you must book by July 15, 2013.
The Terms and Conditions read as follows:
Offer valid May 30, 2013 through August 30, 2013. Reservation must be made by July 15, 2013. Enrollment and registration with Marriott Rewards® is required to be eligible for this promotion. United MileagePlus members must be members of Marriott Rewards and indicate United MileagePlus as their earning preference in order to qualify for this offer. A maximum of 1,000 bonus miles can be earned per stay and a maximum of 10,000 bonus miles can be earned with this promotion. Miles earned on all qualifying charges at participating JW Marriott,® Autograph Collection® Hotels, Renaissance® Hotels, Marriott Hotels & Resorts® and Gaylord Hotels®. Members electing to earn Marriott Rewards points are not eligible for this promotion. Please allow six to eight weeks after promotion ends for bonus miles to be posted to your United MileagePlus account. A stay is defined as consecutive nights spent in the same hotel, regardless of check-in/check-out activity. Your preferred airline/miles program reserves the right to change program rules, regulations, travel awards and special offers at any time without notice. Any such changes may affect your ability to use the awards or mileage credits that you have accumulated. All program terms and conditions of your preferred airline/miles program apply. All Marriott Rewards terms and conditions apply. See MarriottRewards.com or call 800-249-0800 for complete Marriott Rewards terms and conditions.
This Marriott Rewards promotional offer is valid for qualifying stays you personally make at participating JW Marriott, Autograph Collection, Renaissance Hotels, Marriott Hotels & Resorts and Gaylord Hotels located in the U.S., Canada and Mexico. Offer not valid on group stays. For a complete listing, visit http://joinmarriottrewards.com/united/properties.aspx.
This is a good promotion – even cheap one-night stays net 1,000 extra miles. If you have upcoming Marriott stays consider participating and earning an extra 10,000 miles.