if you go to pompei and you happen to go to sightsee mt. vesuvius make sure to gho into the gift shop because they have absolutely WONDERFUL jewelery and other beautifully handmade items. It is a little more expensive, but definitely worth it to say, "I bought it in Pompei".
Plaza de SanJose in old San Juan is a nice place to visit during weekends, and evening. Drive to El Yunque, a rain forest and go hiking, it is well worth it.
I love this place! You must walk up to the fort it's fantastic. Bacardi was invented here just FYI. Also love the carnivals and holiday day they celebrate here!