Considering that you're going to spend a few days Watch Hill just might do. They have the pier restaurant which I think is open Thursday through Sunday. Davis Park, to the West, is only a 1 mile walk or a short dinghy ride. They have The Casino Restaurant which is open all week long. I also think it's the only restaurant with an ocean view on all of Fire Island. I've had meals at both locations and give a bit of an edge to The Casino only because they have a wider variety of options on the menu, but they both deliver a good meal.
If your wife is looking for a town feel Ocean Beach is a great choice too. Lots of stores and restaurants but limited availability of slips which I hear are very pricey.
Good luck
--Steve