I researched a lot online before planning a trip to Puerto Rico. There is a lot to see here and I just wish I stayed here for longer than 4 days. PR is beautiful and even though it's a small island, there is plenty to do and it's worth visiting the different cities.
I went to Old San Juan and I loved it, it's beautiful to simply walk and see the history, visit the shops, and eat at many of the restaurants there. It's very safe and I highly recommend walking around here as it's the size of 20 city blocks. There are 2 forts, both have lots of history and it will take hours just to cover every part and read about the history. There are lots of shops, many outlets and souvenir shops which are worth to stop and check out. There are also many restaurants, some of them have the best food so research online which is rated the best instead of walking around and looking which can get quite tiresome.
El yunque is the name of the rain forest there which is huge and very pretty, there are many trails within this rain forest which can be quite a lot of fun and tiring depending on the level of the trail. Some of these lead up to waterfalls which are nice but if you are looking for some thing equivalent to Niagara falls then you will be let down big time. There are small waterfalls here, the biggest is 50 feet which is right off the road. There is plenty of wildlife here which most of them you will hear but wont see if you stick to the trails. I would recommend a visit here but be prepared to walk a lot and have plenty of time if you decide to do the trails.
The best experience out of this trip by far is the bio bay tour to Vieques. East winds along with island adventures have an excursion trip to the island of Vieques which takes you to the Bioluminescent bay there. Vieques is a small island which is part of PR but is an 1 hour boat ride away. This small island which is about the size of 20 miles is beautiful and definitely worth a trip in its own to check out. The bio bay which is best described and explained here (www.biobay.com) was the best experience, swimming at night in the darkness with glowing planktons was an amazing experience. Even if you cannot swim, they provide you with floating belts which are totally safe and let you float in the water. I cannot describe this experience in words, its one of those you definitely have to go and see for yourself.
This trip experience was my first in the Caribbean and I loved it, wish it was just longer since there was a lot there that I could not see due to time constraints. I highly recommend visiting PR and researching online for reviews and information on restaurants, hotels, and things to do.