So you have a big chunk in a 401K, let's use $400,000 for a concrete example. Here's what you do:
Retire.
Roll the 401K into a T.IRA.
Roll $30,000/year from the T.IRA into the R.IRA creating income (this will add to your husband's pension income, and any other income you make) and you will be able to take the standard deductions and exemptions against that. If Pension + Part-Time Work = $40,000 you have $70,000 gross income - $20,000 deductions/exemptions = $50,000 taxable income x 10%/15% = about $6,575 federal taxes.
Rolling $30K/year will deplete your $400,000 T.IRA in about 13 years without considering growth. It will obviously not stay at $400,000 unless it's sitting in cash. If you factor in 7% growth it will take a lot longer than 13 years, but hopefully you get the idea. You pay tax on the value rolled over, so if the market (or any particular stock/mutual fund) tanks one year roll over a bigger chunk and take the tax hit. It will be worth it to move it into the Roth and let it recover over there.
Once it's in the Roth no more tax, ever. You can take it out and it won't add to your income.
If you leave it in a 401K/T.IRA to grow, you will end up paying substantially more in taxes over the remainder of your life.