You can also enter through Robert Moses State Park (you don't need to take the ferry.) There are homes available for rent on VRBO (but typically $$, like 1500$/night for a 4 bedroom). It's beautiful and a lovely place to visit.

I’ve spent every summer of my life on Fire Island, and will be there in August. Here’s the scoop:

It’s about 30 miles long and at most half a mile wide. As PPs have said, it’s broken up into communities all with different flavors.

The gay ones (Cherry Grove and the Pines) are on the east end.
In the West end are a variety of communities. Kismit and Ocean Bay Park are very singles scene - think the show Jersey Shore, it’s pretty awful. In between are nice family communities, in my opinion, Seaview, Fair Harbor and Saltaire are probably what you are looking for.
There are stores on the island so you can by toilet paper and food, it’s just that they are expensive.
I don’t know what the rental market is like but good luck. It’s my favorite place in the world and with no cars, it’s an amazing place to have a family vacation.
The trip to Bay Shore can run you anywhere between 41/2 to 7 hours depending on traffic. We always leave early and made it in 4.5 for Memorial Day weekend. It’s really just as far as the Outer Banks and so much nicer.

What are the best communities for families?

Also one other thing:
The communities are all car-free, so you need to take the ferry. Retail and restaurants on the island are limited and very expensive; everything needs to be hauled over by boat.

Therefore you’ll need to do all your shopping on the main land sand bring a wagon on the ferry filled with your supplies: food, booze, toiletries, paper towels, etc. Anything you want, you need to bring. This can be especially taxing if you’re bringing kids + all their kid crap.

When renting a house, get as much information as you can about what’s provided with the house. For example, do they provide ample toilet paper? If so, you don’t need to haul it. Also ask about protocol for dumping garbage. Some places make you haul out your garbage with you. Again, that’s tiring to haul garbage at the end of your trip.

Great place, but definitely has hassles.

Gorgeous, but it’s expensive. If coming from the DC area, the drive can be a beast. The NYC to Long Island stretch of the drive is horrible. I’d recommend taking the Verrazano Bridge and avoiding the busy part of the city altogether.

Fire Island Pines and Cherry Grove are the gay parts. The rest of Fire Island is family friendly, though some areas are younger singles partying all summer.

I can’t answer your question exactly because I only spent a day in Fire Island two Septembers ago. I’d go back in a heartbeat. It’s gorgeous there and very chill and family friendly. Plus the ferry ride there and back is fun for kids.

Never been and am thinking of renting a house/condo for a 3-4 day stay after visiting family in NYC. Good idea? Please share your experience and any tips re where to stay, eat and visit. TIA