The summers are hot but as my husband says, "you can't shovel hot". So we'd rather be in FL any time of the year, which is better than the 4-5 months of cold, gloom and snow in New England's winters. In the FL summer, as many posters mentioned, you go out early or in the beautiful evenings. We still take our 2 mile walks every day. We golf too, sometimes in the heat of the day, but drink plenty of water and use a cooling towel. The traffic is less, the dinner deals fantastic and the sunsets superb. As mentioned, there are many pools, central air, and verandas at restaurants to take advantage of. Our favorite time at the pool is 4PM.
Vacations can be any time. In winter to avoid TV traffic, or to go farther south to say, the Keys. In the summer you can vacation up north if you prefer, or elsewhere, but TV is nice then too. Just warmer.