A lot of good advice here. Definitely stay away from MTB's unless you plan to actually mountain bike most of the time. For what you describe I'd check out a Giant Roam 3. They are under $500 and are great adventure bikes. I bought a 2018 a few months ago and couldn't be happier. The Trek DS1 is similar as is the Specialized Crosstrail though both a bit more expensive.

The shop I bought the Roam from also does a lifetime service plan for an additional $60. I've brought mine in once for a tune up and a few times just for advice and minor adjustments so it's already paid for itself. Assuming you find a good LBS that doesn't try to sell you a mountain bike for casual riding in FL I'd say it's worth the additional cost.

As for accessories, a decent helmet is a must. Everything else can come later. You'll want a bottle cage if you plan to ride for extended periods. As you start riding farther out you'll want to put together a small repair kit, maybe a cell phone mount and a bike computer if you want to be able to track your progress. None of that is mandatory though aside from the helmet.