My kids and I just came back from 5 nights at the La Concha Hotel. We hhad a great time! It is a beautiful hotel and I have to give a big shout out to Louise, the concierge there. She is FANTASTIC!
I really recommend Puerto Rico as a family vacation. Old San Juan is wonderful. There is the rain forest, "El Yunque" to visit and all kinds of snorkeling, swimming and water activities.