Should I expand my one-act play to a full-length?

Almost every playwright I know (myself included) who has written successful one-act plays has, at one time or another, been told by well-meaning folks (including theatre professionals who should know better) that the play ought to be expanded to a full-length.  And, whenever that's attempted simply by stretching what's already there, it results in transforming a tight and focused one-act into a meandering and overwritten full-length.  That being said, if you feel that there's more story to be told (new events in the journey or new subplots that impact the main plot or new characters that might add complexity to the story) then go ahead and give it a try.  But my rule of thumb is this: if there had been a full-length play there in the first place, that's probably what you would have written.  Don't be swayed by enthusiastic people who love your one-act so much that they insist on more.  Sometimes less is more.  And, to be further cliché about it, remember the old showbiz adage:  "always leave ’em wanting more."  In other words, rather than reworking an old one-act, wow 'em with a new full-length.