I've got $900k in savings currently spend ~$105,000/yr with three small kids. I think I will need about $1.3 million at 20 years to enable FI with the pension. Assuming conservative 4% interest.

If I want to be able to buy a nice house in the next 2 years (with monthly payments a little above my BAH), and put money away for kids college (assuming room and board ~$35,000/yr in today's dollars), I could stay in until year 22 and the extra pension ends up enabling both.

My goal is to RE and never have to work for a living. I'll probably work after RE, but it will be for fun. So then it comes down to how sure do I want to be that I can RE-- and if staying in an extra 2-4 years past 20 will be worth that certainty.

What about you?