Pretend the $20 million is guaranteed, and if anything will increase slightly over time.
What problems could be significantly improved for $20 million?
(I am dreaming of winning the $1.55 billion Powerball drawling. Then taking the lumpsum, posting taxes, investing, and spending 4% each and every year. I understand that the actual may be more, or less than the started amount.)
First, I would find out who I need to pay to find people for jobs I need done. I hate dealing with people. Also, I suck at knowing who to call.
Then, I would get someone to rebuild my house, better, stronger, faster. My house is nice, but it has some major issues. Mold problems I can't fix. Lousy insulation. Floors that let us hear everything going on between levels. A ridiculously small master bathroom.
More importantly, I would pay for a better education for my kids. I homeschool for various reasons (via videos and on a curriculum), and while their education is solid enough, my daughter could use someone better than myself for subjects where she struggles.
Once everything is set up with a lawyer, I would set aside money for close family members.
Oh, and I would hire a maid and a chef for my house. I like cooking, but I also like not needing to cook. And who enjoys cleaning?
My wife would surely either pay for landscaping for our yard, or she would buy a boatload of plants and do it herself. Probably somewhere in between; we've got a rocky yard that no amount of personal labor will make manageable, but I think she enjoys the planting.