You mention the Marriott as a hotel where the two of you like to stay. A good choice is the Marriott Rewards Credit Card from Chase. You can earn three points for every dollar spent at participating Marriott locations and one point for every dollar spend on other purchases. The first year there is a $0 introductory annual fee, the annual fee after that is $45.
Now, if you'd like to kick the rewards up a notch, consider the Marriott Rewards Premier Credit Card from Chase. You can earn five points for every dollar spent at participating Marriott locations, 3,700 Marriott locations, two points for every dollar spent on airline tickets purchased directly with the airlines, and at car rental agencies and restaurants and one point for every dollar spend on other purchases.
This is a Visa Signature card, which means there are plenty of perks. You can see a list on Marriott's website.
This card does offer an introductory annual fee of $0 the first year, after that there is an annual fee of $85, so you'll have to decide if the extra benefits are worth it to you. Both of these cards offer the same variable purchase APR. The rate isn't bad for a rewards card.