This isn't investment advice, just throwing some spageti on the wall to think about.
1. Rather than a traditional CD, you might look up a 'market linked' cd. Still FDIC insured but now, instead of the bank taking your money and lending it out for credit cards, loans, other.... it might be invested in the stock market or commodities or other underlying asset. Just like a traditional CD which might have someone file bankruptcy on their loan or credit card.....YOU the CD owner, do not suffer that risk, that belongs to the Bank. On a market linked CD, even if they put funds into commodities or stock market, YOU do not bear that risk.....you bought a FDIC insured CD. The bank takes that risk. YOUR risk might be the credited interest rate. You might have a floor of zero (if market goes down) but a maximum of 10% (if market goes up) Might be worth looking into but your local "banker" won't necessarily have access. If the bank has an investment advisor on their staff, THAT is the person to talk to. You need a securities license to sell one of these.
2. Maybe learn about a Municipal Bond. Virtually every state (and various counties in each state) write/sell muni-bonds. If you buy a bond from the state in which you live, then the interest from the bond is tax free from both state AND federal taxes. if you have sufficient horsepower, you can buy a basket of them. Why? These bonds typically pay twice a year so every six months. If you bought six of them where your dates of interest payments were:
January/July
February/August
March/September
April/October
May/November
June/December
You could build a stream of monthly income that is totally tax free. Note that (especially in a rising interest rate market) I'm not a fan of bond FUNDS.....but rather the individual bonds themselves. Why?
If interest rates go up, (bond values then go down) so in a fund, you might be buried for who knows how long. If you hold individual issues, you can wait until maturity and get your money back.
You can ALWAYS sell the bonds. Your pricing would be subject to interest rate movements but if this is bedrock, long term money, then just take the tax free earnings. If you don't need it, plough it back into another round of bonds to increase the tax free cash flow.
Probably 20 years ago, working at a bank.... had someone come back that a banker coudn't help. He had just come into maybe $400K and what to do.... after talking with him, I mentioned the above idea. Found a baskket of bonds, created a spreadsheet so he could see the cost, the monthly income. He said he'd like to try it.
Roughly two years later, my phone beeps at my desk, "Mr. Jones is calling you". Same person above.
"Hi Richard....long time..... do you know where I am?"
(boy was I full of smart alec comments after two years!)
"How you doing? Nope, I've got no idea where you are!"
"I just left my CPA's office.... wanted to let you know that I had over (I forget) $20,000 of tax free income from those bonds and I didn't owe a PENNY of tax....!!! I just wanted to call you to thank you!!"
NOBODY ever calls me back to thank me like that. I was genuinely impressed and touched by his call.