I only do it the night before a very early flight.

TWA hotel at HFK is really cool and fun! Hot tub overlooking flights taking off and a TWA museum, gym, restaurant, bar.

Like others, I have moved to an airport hotel on the last day before an early morning flight, especially if I have a car return. I have also stayed at one if I’m transiting the city, even if I take public transportation downtown for the evening to get dinner.

I've done it for one night before a early morning flight back home from Europe, or when I had a super late arrival in a city and the airport was kind of far outside the city.

In Orlando it is significantly cheaper and not much further than staying at other outside the park hotels. I don't do it, but know of other who have, especially when rates are inflated due to a large convention.

We do this when arriving late. We flew into Calgary to visit Banff, and our flight was due in around 10pm. We didn't want to drive to Banff at night so we had a room waiting for us at the airport hotel, which was so nice to just sleep. In the morning, we picked up our rental car and started our trip.

I always do this when flying out early.
Free parking for weeks and shuttle to gate.
The night before, a night on the town near airport.

I stayed a couple of times, one time we were staying in a city that is about 3 hours from the airport, so the last night before our early AM flight, I booked the hotel near the airport. Otherwise, we would have had to leave our hotel at midnight to make it to our 6 or 7 am flight.

Another time, I had a connection, where I arrive 8 pm and my flight next day is 3 pm, in a city that has lots of traffic, so just got a hotel near the airport. It saved me 2-3 hours of taxi time, and $, it was cheaper than in the center, and the hotel provided free regular shuttles to / from airport.