Congratulations! I am in a similar situation with my work, as I am 49, and have been working for the same company for 27 years. I can definitely sympathize with feeling burnt out, as I have come to that realization about myself also. I did recently move into a new area, and I am working on a lower stress, yet somewhat fun project right now, but we just experienced layoffs again last week. Honestly, while people were freaking the F out, I was fantasizing about what I would do, and sort of hoping to be set free myself.
If my company were to make the same offer, I would be hitting the button myself, as the severance package is definitely a deal maker! It would be very easy to walk out of the door with a $100k bonus to take a different job, potentially making considerably less, doing something I really enjoy, instead of continuing along another few years.
Right now, I am planning to work until 55 in order to ensure that I have enough income during my daughter's college years, and to qualify for retiree health insurance, after which both my wife and I will be pulling the plug together (unless the offer me a 'package').