If you are not going to fly regularly, don't worry about status miles.
You need 18000 for AC Prestige, 35000 for Elite. Your trip to St. Pete's will probably earn you a little under 10000. Without some more to bulk that up, you won't have any status flowing from that.
All other things being equal, I would say stick with the program you are in--it doesn't make sense to split your miles between multiple programs unless you earn enough to ensure you use them all.
However, if the fare difference is substantial, then that's probably your best option.