I think we'd tell a select few (immediate family), but not disclose the figure.
Firstly, we'd pay off our debts and buy ourselves an amazing home. Also purchase a few investment properties.
Then we'd pay off my parents mortgage, buy a property for MIL (who is on the pension and renting), and give some money to SIL and put some money in an account for my brother.
Have a splurge on travel & buy new vehicles. Make some generous donations to some worthy charities. Throw a massive fancy party for all our friends. Renew our wedding vows in style.
Consult with a financial adviser to work out how to make the rest of the money 'work' for us.
I'd also use the money to ensure my DS had the best possible support for his education.