with AA or UA/CO. I have status on both alliance and I can confirm that yes, there is a PRIORITY line per se on both terminals. However, it may not be like what you might be familiar with. I'm based at ORD, and there is a "special" elite ONLY check point line at the UA terminal and also at the AA terminal. SJU version of "priority line" is just a separate roped area that is next to the "regular" line. Sometimes it is closed, but I go through it till I get to the agent checking ID's, just show your BP and ID and you are good, if they mention anything, just say you are elite. However, once you are passed the id part, it is a "common" line from there.
Depending on when you are traveling, there may not be that much of a line at all. Safe travels.