Since you'll probably need to leave the resort verrrrry early to make the start of the marathon (I think the buses are transporting participants somewhere in the 3:30-4:30am range ?? ), you might need to have something available in your room since Olivia's will definitely still be closed at that time.
I think the marathon usually has a 6:30am start, but you'll need to be at the staging area long before that. Better plan on having something in the room.