SIM Cards in Puerto Rico and the Virgin Islands

[phorvati]

My wife and I will spend next long while in Puerto Rico and the virgins. Is it better to purchase a sim card locally in Puerto Rico or the virgins, or should we get it in the states. We would like to be able to get free incomming calls from the states and call the US at lowest possible rate. What kind of rates are typical?Since my wife is pregnant we also plan on making local phone calls in PR and VI.