I second the FIre to do good in the world. I have actually contemplated this a lot myself. I know either my parents or my in-laws would both feel deeply dissappointed if I used inheritance to lounge and do nothing for the rest of my life, however I would love to stop the daily grind. I hope to be FI long before I have to worry about what anybody would want. I'd like to think that I know exactly what I'd do in your situation, though would need to make sure my wife was onboard 100%. This is actually my plan for when I reach FI anyway, it'd just start sooner.
1. Stop working for other people. Time is too valuable of an asset to wast toiling.
2. Use the inheritance to set myself up in a living situation where my essentials were maintained with little-no effort. This would include big things like moving to a paid for house that would have low overhead costs, and is up to date (probably built new) as well as small things like ensuring that the organization and design of the home is best suited for easy maintenance (like making sure lawn design is EASY to mow). Purpose of this is to free up time, and be free from worries.
3. Use time/skills that I have to make a REAL impact on the world. Start small, volunteering, teaching, etc. and work up to big things like starting charity foundations. I have a charity/volunteer list already going. I would front time and effort, NOT money, unless it was a short term thing, or I had a charity category in my budget that it came from. My time is too valuable to force myself into a position to go back to working for others.
I try to keep in mind that things that I am able to do may be things that may be hard/expensive/overlooked for others. I think most people who attain FI have valuable skills that helped them reach FI (even if it's just being good with money.) In my case I try to pick up new skills as they are required.
Leaky faucet at the homeless shelter? My time/labor is free, ideally get parts donated by local business. Food bank always needs donations? Again, my time/labor is free. Try to get a farmer to donate/lease (free) 1 acre of farm land on a continuing basis and start a high school community service farm? Most high schools have a community service requirement anyway. Once set up I can move to other things, or can do the same thing in a neighboring city/town.