A lot of good opinions on here already but I figured I would share mine.
I don't personally have any short term rentals in NH or Florida but do have one just over the border in Southern Maine. I will speak more so on the Northeast market as I really don't know the Florida STR market.
Parts of Nh are going to have a great year round draw to them. The lakes region which benefits from summer and winter travel is a small, well-kept, secret market. The STR's here are primarily second homes that out of staters have converted over after realizing the returns they could get. Because of this - I don't believe there are many huge players that are truly running their properties as businesses.
The lakes region benefits from some of the nicest bodies of water in New England as well as close proximity to some excellent skiing, snowmobiling, snowshoeing and other winter activities. With several large cities within driving distance 6+ hours - the demand for recreational activities I believe is a safe play without the requirement for airfare.
Gregg posted a great article with information into one of the more popular markets (Conway) just announcing a win for property owners. This is huge for a lot of local owners as well as the STR market in NH and potentially the surrounding states. Although others have said it won't necessarily impact what other cities do - I personally think the courts decision is better for STR than if the opposing opinion had won. Conway is one of the largest markets in NH and personally where I would like to purchase next.