I got the impression that the restaurants in the Marina were not tied to the Marriott in any way. We did not do any food packages through Marriott and only ate breakfast at the hotel once. The other mornings we wandered over to the Hook Up so we could get a walk in and grab breakfast with a nice view of the Marina. We did frequent the lobby bar in the Marriott for drinks and apps quite a bit though, which usually ended up being our dinner. It rained most of the time we were there, so we didn't really venture out of the Los Suenos compound at night...I'm sure it would have been perfectly safe, we just chose to stay on-site and enjoy the atmosphere around the resort and marina in the evenings.

If your girlfriend is in to cooking, we went to a place that grows their own black pepper, spices and vanilla and you can purchase on-site. It was a pretty cool little side trip on the way to Manuel Antonio.

http://costarica.com/attractions/villa-vanilla-farm/