Where else can you drive 3 hours and go from dense rainforest to absolute desert, spend your morning snorkeling pristine reefs and your evening deep in the mountains, and see a mix of old and new everywhere?
I live outside the metro area and there are definitely 4x4 only areas as far as transportation and it becomes quite rural pretty quick in the hills. Not to mention the chupacabra.
I've never been to Puerto Rico. Rainforest I can imagine, but where on that island is there a desert, even a relative one?! When you say "absolute desert" I'm imagining, I don't know, something like the Sonoran Desert.
Wear a big hat, go before 8am, and stop by the salt flats.
Average annual rainfall of 24-39" is not exactly anyone's idea of a desert (I believe 10" a year is the typical definition), though looking at the photos it does appear to be more similar to the transitional area in Texas Hill Country, for example, with short trees and more shrubs. Certainly a far cry from the lushness that I expected to encompass all of Puerto Rico.
Offhand thought 24 inches in a hot climate doesn't go as far as 24 inches in a temperate one.
Washington!
Hawaii, except I didn't drive, I walked; and it took half an hour, not 3 hours.
But 100% worthwhile.
And yes, you can get to the desert driving 3 hours east (albeit into Oregon)