I'm in a similar boat- 56 with 30 years, lead a group of about 10 and don't want to leave them in the lurch. We have a lot of trouble hiring because my profession is a small niche without a lot of new entrants. I plan to give my supervisor about 6 months' notice.

Question- could you go back to working from home a couple days per week? You have solid evidence of your effectiveness and have the negotiating leverage that you can walk away. I'm sure you're not the only one who realized that 3 hours of travel is draining and doesn't help efficiency.

Government pensions are a sneaky carrot hanging in front of you- work just a little longer for more money. Too many of my colleagues have chased the carrot until their health is failing so they don't get to enjoy retirement. It sounds like your pension plus investments (plus social security?) is sufficient. What would you do the first year of retirement in your mid-50's? Would that add more value to your life than an extra $250 per month for life?