If I recall correctly the airport is not too far from the pier. Keep in mind that San Juan is a cruise city so they are ready for people like you (and your party). I would just look for a van-style taxi when I arrive. The worst that could happen is that you need two smaller taxies.
Or, if you want to be sure you have a van you can pre-book a car service (remember you have luggage too). Just search online for one.
I am the editor, but I also speculate, ask questions and play devil's advocate. I reserve the right to change my mind.