UBER has long been known as the cheaper alternative to taxi service to get to the Luis Muñoz Rivera Airport (SJU) but, starting tomorrow,
UBER can be used for arrivals as well. UBER will pick up from zones A and B for the time being (the area of Delta, Spirit, United, Southwest JetBlue).
You might find that UBER takes longer than a taxi to pick up at the airport. I have seen it take as long as 20 minutes to wait for an available UBER. My advice, if the wait is too long for you, consider taking a taxi. The taxi stand is directly outside the baggage area of terminal B, and also just to the right of the JETBLUE terminal (terminal A). Uber is typically about $12 to $18, while taxi fare is fixed and to Coqui del Mar Guest House is about $22 (depends on luggage).
To the airport, UBER is definitely the cheapest and easiest way to get to the SJU airport, and is typically about $8 to $10 from Coqui del Mar.