I live in The Villages, FL - the largest retirement community in the world. It has 100,000 residents, more or less. The exact number varies, because we have a lot of snowbirds. I moved here because DH could not tolerate the winters in Maine, a place I love. He moved to Maine to please me, so I moved to Florida to please him. It's worked out well for both of us.
We are not on the coast. We are in the middle of the state, an hour north of Orlando. So, as others have noted, we do not have the ocean moderating temperature, but we also have very little flooding. Our house sits 89 feet above sea level, so climate change would have to be quite drastic to affect us.
About the hot summers: people shift their outdoor activities around. Early mornings here are quite lovely, in the 70s. DH and I frequently ride our bikes to breakfast. On our way back, temperature will hit 80, and by noon it's 90 or higher, depending on the day. We'll have lunch and take a swim in the pool. There are lots of community pools here, but DH is not a fan, so we have our own pool. Temperature peaks around 4pm, often followed by thunderstorms, which are both lovely and violent. Weather cools down again around dusk.
The Villages sprays for mosquitos, and obviously there are many opinions on the advisability of it. I can tell you that the only insect bite I have received here was from a wasp, and really, I should have looked where I was pruning. Gardening, by the way, is ENTIRELY different from the northeast, and it is taking me a while to get used to. Heat loving plants grow ferociously. The tiny rosemary sprig I carefully nurtured in Maine? It's a tree here. You can grow roses, but you need to select varieties that have been bred for this climate. Some herbs do better than others. The lizards love my thyme and dill, so I have trouble keeping those.
I spent a week in July in Maine, visiting my college roommate, and it was only about 5 degrees cooler than Florida with no air conditioning!
As far as costs go, we have an electrical co-op here, so electricity is very reasonable. We average $150 per month for an 1800sf house, keeping the temperature at 74, the highest DH will go without complaining bitterly. He was in IT and has a ton of gadgets plugged in, so people could do much better if they tried. We spend very little on gas, even though we have a heated pool. Water is much more, because we have an irrigation system like everyone else here. It averages about $100 per month. Our homeowners insurance is about the same price we paid in NJ and Maine. Car insurance is cheaper than NJ but much higher than Maine. Real estate taxes are $2500 per year, compared with the $12,000 we spent in NJ and the $4000 we spent in Maine.
Overall, we spend much less here. I wear t-shirts from Goodwill ($2.07) and jersey shorts from Walmart ($5) most days. There are maybe two weeks of what could possibly be called winter, and even that means a jeans jacket rather than a coat.
I like it. It's easy to live here. People are friendly. There's plenty to do.