Haven't yet, but I am planning for my retirement early (I'm 52 in a few more weeks) If I may offer something, I would suggest you research a Roth IRA to roll the 408b into, maybe split it into two, one for you, and one for the missus. If any of the 408 assets are company stock, you are better off holding the shares in a taxable account rather than cash them in. That separates them from assets which may be non-taxable under the codes. A lot depends on how much is in the 408, if the amount is minimal, you can decide if you want to take the hit in taxes and go for a full divestment. If there is a considerable amount, you may wish to consult a financial advisor (if you have stocks, talk to your brokerage, they give excellent free advice!)
I would not go back to work part time. Incorporate yourself and file as a business with your state, then hire yourself out as a private consultant. Tax write offs for the business for travel, office supplies, mileage, vehicle depreciation etc......your old company can hire you on a contractual basis, or per diem. Gives you the most tax breaks to mitigate the reduced SS benefits.
Best of luck to you....this getting old stuff can get complicated!