AA has gobs and gobs of flights to San Juan, 6 or 7 a day, if I recall. The boat will take hours (overnight) and gets you to Mayaguez , no idea where that is in relation to SJ, and costs as much all told.
OK they have 6 a day, pick one: (The 7 a.m. and the 2:30 are real planes with jet engines and a_s_s room)
Flight Frm Departs To Arrives Typ Meal Freq Begins Until OperatedBy
AA 790 SDQ 7:00am SJU 7:59am 757 MTWTFSS 24JUL04 07SEP04
AA 5425 SDQ 10:25am SJU 11:40am AT7 MTWTFSS 24JUL04 07SEP04 OW/AA EAGLE
AA 5347 SDQ 11:45am SJU 1:04pm AT7 MTWTFSS 03AUG04 07SEP04 OW/AA EAGLE
AA 314 SDQ 2:30pm SJU 3:33pm AB6 MTWTFSS 24JUL04 07SEP04
AA 5223 SDQ 4:45pm SJU 6:05pm AT7 MTWTFSS 24JUL04 30OCT04 OW/AA EAGLE
AA 5427 SDQ 5:45pm SJU 7:03pm AT7 MTWTFSS 24JUL04 07SEP04 OW/AA EAGLE