We're fortunate to have a very good financial advisor whose top priority is a lifetime stream of guaranteed income.
Our primary source of income will be laddered annuities that will pay a fixed amount until we are both gone. They have locked in cash values, so if we don't live a long time, any remaining value will go to our heirs. My mom cleaned up on her annuities, living to age 90 and drawing $150,000 more than their cash value.
Social Security will be our secondary source of income, and all the models project it alone will be more than enough to cover our expenses. Of course, one of those checks goes away when one of us dies, and we have enough life insurance to replace 10 years of Social Security income.
My mom must have out frugaled your FIL. She passed away 10 years ago, and I managed her finances the last 13 months of her life. Her Social Security was only $1,250 a month, but her monthly expenses were only $650 a month. She had a pension and her annuities as pad for her income, but that all went into savings. But her house was paid off 53 years before, she paid cash for her car 10 years before. Her long term care insurance covered all but $300 a month of her tab, so even then, her Social Security was more than enough to cover everything.