Well done!
The 457s allow withdrawals at any age without penalty, so as long as your employer's allow partial withdrawals I would leave them where they are and withdraw anything you want to actually spend from there.
The 403b I would roll over into an IRA once you retire and then start converting to roth.
Between your 457 withdrawals and traditional to roth conversions you should certainly use up the standard deduction and personal exemptions (no tax on that), and probably the 10% bracket. Then for the 15% bracket you should consider what conversions you might want to make vs using the space for capital gains harvesting of any taxable account you have since that would be in the 0% capital gains bracket. If you have pensions that will of course take up some that space first.
You may decide you want to even go into the 25% bracket or beyond. Your goal should be to equalize your tax bracket throughout retirement such that forced withdrawals in the form of Require Minimum Distributions (RMDs) once you're 70.5 don't push you into an even higher tax bracket.
Another complicating factor: if you expect to be on ACA marketplace health insurance you may or may not want to also manipulate your income to stay under certain other caps independent from tax brackets as the loss of subsidies can act as another form of tax. If this is the case you might choose to limit your withdrawals and conversions until you hit medicare age, but keep in mind that this will likely push you into a higher tax bracket later in life, so it's a tradeoff.
As far as what to do now, have you contributed to IRAs for your wife and you already? Since you must be over 50 given that you're making catch up contributions to the 403b and 457s that would be another $6000 each ($5500 regular plus $500 catchup). Depending on your MAGI (modified adjusted gross income) you may not be able to contribute to a deductible traditional IRA or to a roth IRA. If you can't do either you can look into a making a "backdoor roth" contribution.
Here are the income limits for make a deductible contribution:
https://www.irs.gov/retirement-plans/plan-participant-employee/2016-ira-contribution-and-deduction-limits-effect-of-modified-agi-on-deductible-contributions-if-you-are-covered-by-a-retirement-plan-at-workHere are the income limits for making a direct roth contribution:https://www.irs.gov/retirement-plans/plan-participant-employee/amount-of-roth-ira-contributions-that-you-can-make-for-2016
If you already made IRA contributions and as bacchi mentioned, if you don't have an HSA, then go with a taxable brokerage account.