Lots of perfectly valid answers here about decent humane things to do with the money and power, and I certainly hope I would do things like end homelessness or otherwise meaningfully improve the world.
That said.
I'd build a full-scale, 1:1 replica of the USS Enterprise, NCC 1701-D, from The Next Generation. I'd run it like the Biltmore; technically it would be a private residence, but I'd charge people to take tours. But any time I wanted, I could close it down for a few days and just hang out on the bridge or in main engineering and vibe out to the THRUM THRUM THRUM of the warp core.