Be brief, be transparent, and finish strong!
This is certainly not the time to bring in a laundry list of reasons you are leaving, though there may be a time in the future over a coffee/drink where this could be beneficial, but during the resignation is not the time. When resigning, whether in person, over the phone, or email, simply stating your final decision has been made and you’d appreciate their honoring your two weeks without a counteroffer would be greatly appreciated. While counteroffers are cause for endless conversation, the ideal scenario is putting in notice, transitioning work, and leaving amicably.
Transparency is just fine, though should be handled the right way. People don’t leave jobs, for jobs which will do less for them and their families. This transition is absolutely an opportunity to better the situation for you and your family and getting into the intricacies of that are not needed. A simple, “I am putting in my two weeks notice today, I am moving on, this was a very difficult decision but it is one that is best for me and my family at this time. Thank you for your understanding and I will begin transitioning my work immediately.”
Finally, use the last couple of weeks to continue building relationships. You NEVER want to burn a bridge, because who knows…..what if your new boss leaves and your old one is hired to replace them. Leaving a positive, hard working imagine throughout your final days will certainly be noticed. While it may be tough not to check out, use your final days as an opportunity to leave on a high note.