Hello, and thanks for writing.
Actually, it is not that far drive from Rincón to the caves, however, bear in mind that the Camuy Caves can get really crowded specially during june - july, so crowded that often tours for the rest of the day are closed as early as 11:00AM. I tell you by experience because I have tried to get there myself and the person that answered the phone told me that the park gates where closed for the day and it was 10:30AM! So I'd say the whole Camuy Caves and Arecibo trip should be considered as a one day thing.
When doing our yearly family north-west trip we normally stay over one night. That way we can get early to the camuy and arecibo attractions, then relax the rest of the day cause suppose you get to the caverns early (say 8:30AM and that's late already!), then spend the rest of the morning to enjoy the park you can expect to be out of the park by 11AM - 12PM or so, then drive to arecibo, get some lunch and spend the early afternoon in the observatory. Then stay somewhere and wake up early the next day for some beach fun aguadilla, Crash Boat beach is a good choice.
For me, since we love small and intimate places, we always stay at Three Brothers Guesthouse in Isabela, a short drive from Crash Boat beach in Aguadilla and not too far from Rincón. It is clean, simple and inexpensive. and the breakfast buffet is OUT OF THIS WORLD, for about $5 per person. Of course it is small and run by its owners, but for us its perfect.
http://www.puertoricoexplore.com/Detail/465_Three_Brothers_Guesthouse.htm
Hope this helps!
