This really isn't advice on how to get there. I lived in PR for a year and a half and my most memorable experience was going to the bioluminescent bays. I went to one on the main island and one on Vieques (there's another one near Fajardo). They were absolutely amazing and not to be missed. You can find some of my other favorites on my site - Travel Savvy Family. Here's a link to the PR posts. I hope you have an amazing time! Oh, and make sure you get some mofungo!!