And now for the female point of view.....
There are 2 nice hotels in Ocean Beach. One is called The Seasons Bed and Breakfast. They have lovely small air conditioned rooms, and offer a complimentary continental breakfast in the lobby. The phone number is 631-583-8295.
The 2nd hotel is called The Palms. It used to be Jerry's Accomodations, which was beyond gross. However, this is a brand new, re-done hotel, and I understand it is very nice, though haven't actually seen it. Sorry, don't have the phone number.
If you are looking for EXCELLENT food in a beautiful outdoor sunset setting, I would select Hauser's Hideaway in Ocean Beach for dinner, and then you could move on to a bar in Ocean Beach, like the Mermaid or the Alligator. Don't know if Hauser's will let you dock there overnite though, and no electric, etc. even if you did.
However, if food is not important, I would choose Flynn's for a few reasons. It is always a happening party there. The girls can be as loud and crazy as they want, and there are usually lots of hot young bodies around. The sunsets are beautiful there as well. If you can get an inside slip, it is a decent overnight marina, and they give you a credit towards the restaurant/bar.
In addition, at Flynns, you have access to the hotel and pool up the block, where you can gather for a drink by their bar, or a pool party. The phone number for Flynn's is 631-583-5000, and for the Fire Island Hotel is 631-583-8000. Best of luck. Sounds like fun!