Burning Question - Walking Off the Beaten Path

Today's question is taken from this week's 'Ask a Pro' column from the Paizo blog and I think it is one question that many DMs would have face once when running a published adventure/campaign.

You are running an Adventure Path, and one of your players is ignoring the obvious hook. Do you gently nudge him in the planned direction, or do you go with the flow and see where this digression might take you?

As the DM, I usually try to make my plot hooks as interesting as possible for the characters to go my way. But in the event of a derailment, I eventually try to tied their current course of action back into the main plot, skipping or replacing missed encounters if I have to.

Another method which is a last resort and I'll only use it when I'm really stumped for ideas of steering things back into the right direction or when things are getting out of hand, is directly telling them what the plot hook is. Normally my players would take a hint but this could not be fulfilling if the characters seem to be enjoying what they are doing now than being forced to go on the tracks.

What would you do?