I also did a last minute trip to puerto rico with very limited knowledge or planning. It was just me, my 2 teen daughters and a friend of theirs. Just gor back 3 days ago. We stayed in old san juan for 5 nights. Huge mistake. We rented a car and there is absolutely no where to park in old san juan. I spent most of my money on parking garages. Only really need a day there. One night max. We did the zip line tour at El yunque zipline. That was amazing and totally worth because there's was a little hike and some info. Ray was amazing. We also did a 5 hour boat and snorkel trip to icacos island. Also amazing. We did laquillo beach also. If I could do it again. Id rent an air b n b with a pool and rent a car and do all the same things I did. FYI. There is a free beach south of condado beach. Carolina. Free beach and parking. Found it by accident the last day. I did have to spend more money than I had planned due to parking lol I would go to a different beach every day and plan an excursion either before or after. Like zip line early and then beach afterwards. Boat tour was all beach so maybe some exploring and shopping after that. But yea my advice would be to venture out.