I would have done pretty much what they did: do a couple seasons with the original premise, which was about all the good years the premise had in it, and then try to hang onto my job with my finger and toe nails by stretching the premise till it squeaked.
It's nobody's fault that the premise wasn't infinitely stretchable. It doesn't make it a bad premise. But who willingly decides to hit the unemployment line in a business as fickle as entertainment? Of course they kept the show going as long as they could.
However! If I were a bold risk-taker, not only on my own behalf but on behalf of dozens of hard-working people with families to support who might not appreciate me playing fast and loose with their livelihoods (well screw them, no guts, no glory and I don't care if Suzy needs braces), I would have had the series continue along the lines implied by the Xmas episode where Chuck sees Sarah commit cold-blooded murder, and rather than just sweep it under the rug the next episode, I would have taken that idea where it naturally leads, namely out of the comfort zone of a cute, fantasy-based show where things never get too emotionally real. Given the sketchy ratings the show has always had, that decision would be, oh, 85% likely to result in cancellation sooner than if I had taken the orthodontist-friendly route.
So it all depends on whether I'm willing to be an utter bastard for Art.

Someday, I hope to be in that position so I can see what choice I make.
thought the Vulcan seem curious and introspective. He doesn't seem pissed off to me.
He seems to be incredulous about something, such as, "Did you really say that? I can't believe my ears!"