Well, IMO, it's not clear that the priority tags have any effect (I haven't noticed any correlation between whether a bag is tagged/untagged and when it rolls out the chute onto the belt in baggage claim.)

However, it does make you look cool on the airport shuttles and when you're checking in to your hotel

So I'm not sure it's worth the effort to ask, although I've had good luck getting the tags since becoming 1P...

Dan