I did some riding in Puerto Rico on small beach front access roads and trails near the beach. Very nice. And, I would have loved to have been on a beach cruiser in "Old" San Juan. A nice way to explore all of all the nooks and crannies of that fascinating part of the city.
But, roads that led from one town to another were often two lanes, and narrow. Lots of people driving too fast, and passing where there was no safe place to pass. And, lots of twists and turns, so a driver could come around a curve and be rather surprised to see a bike.
The hotel that rented me a beach cruiser was charging something like $15 for a half-day. If I had been staying more than a week, it would have been cheaper to buy a $70 K-Mart bike and give it to someone as a gift when it was time to leave.
Off the topic...when I got off the ferry leading from "Old" San Juan back to the main highway, there was a bike club gathered at the ferry station. They were showing off their restored Schwinn beach cruiser-type bikes from the 1950's, as well as some new beach cruisers, dressed up in "low rider" style. It was amazing to see how many long hours of work, and how many dollars had been invested in these bikes. Too pretty to ride, though.