Unless the security light is on in the dash, I doubt that it's a lock cylinder issue. The key sticking in the ignition is a common symptom of a bad ignition switch, so I beleive that is your issue. Here is a write up from the Grand Prix forums on how to change the ignition switch, as the Regal and Grand Prix use the same switch.
http://www.automotiveforums.com/vbul...d.php?t=653340