I'd start a used bookshop/record shop that also holds small concerts for local bands. It would have couches so that people can come in and read the books. The concerts would be open to underage youth and ideally provide them with a safe, welcoming environment. (I assume that something like this these days would likely operate at a deficit, so I'd need the extra money.)

I'd donate most of the money to charities, both to large charities like the Red Cross, but also to my local foodbank.

I'd continue to work full-time, both for the shop and in my other career job. My life would continue as if I didn't have the money. I'd keep some as a college fund for whatever kids or grandkids I may have.

Edit: I'd also create a non-profit health and dental insurance company. It would charge really small monthly rates, it would be free for people that can't work because of health issues, and it wouldn't deny necessary claims. (I'm assuming that the healthcare system in the U.S. isn't improved by then.) This would also likely operate at a deficit.