From a reader:
Just had a question. I’ve seen you write some pretty solid career and interviewing advice. How about this situation – I turn in my notice and my boss offers me a raise and a promotion. How do you handle that?
One thing keeps popping out in my head on this one... if there was a promotion and a raise so handy, why didn't the boss already offer that? Why did it take the threat of leaving to motivate the boss? There's no way I would continue employment at a place like that.
Get out of Dodge.
From a more sanguine point of view: once you have given your notice, you must keep your word. It is a matter of integrity. Whatever motivated you to leave is still true, even if they offer a change on the surface. Also, the chances of being let go by the company in the 18 months following such a situation are incredibly high. If I recall correctly, there's twice the chance the company will let you go in the next 18 months than there is that you will leave of your own accord.
When you leave, do so on good terms. You never know when paths will cross again.
When you leave, offer a two-week notice.
When you leave, be prepared to be escorted out that same moment.