Marriott is updating their hotel categories in March, but the good news is they are giving us advance warning so we can plan accordingly. Some hotels will go up in categories so you would want to book those now to get the best deal. Some hotels will move down in category so you would want to wait and book those after the change.
Marriott organizes their list by hotels moving up and hotels moving down and then by brand. Some of their hotels in Canada are moving down. A lot of hotels in Houston, TX are moving down. Some in Mexico are moving down.

You can check out the whole list here.   Let me know in the comments below if you find a great deal!