Mrs. FtG is suggesting I get a newer car. Currently I’m driving a 20-year old Corolla which is, in fact, in better shape than her 17 year-old one. So I’m thinking something like a 3-4 year old Mazda 3. I’d love to have a hatchback again. With a ton of money I’d go for something like the new Corolla hatchback instead.
Dream big, I say.
Fix our 120+ yo house. I figure $100,000 would do it. $150k if I decide to put a basement under it.
And buy a new pickup.
I like the idea of homes in different places. I think maybe 10 places that I would like to explore more - NYC, London, Japan (not Tokyo, though), someplace in Morocco or Tunisia, Italy, Spain, Greece, Sweden or Norway, and so on. Then I could take extended stays at each spot at the best times of the year for local exploring, so that it would take me several years to cycle through them, and then start over. I would have a cook and housekeeper/factotum travel with me, to take care of me. We would all travel first class all the time.
These aren’t really modest things, but you did say a gazillion dollars. I mean, yeah, I’d pay off my mortgage here and get a few things fixed up that need it, but then I’d probably sell this house since I wouldn’t be spending hardly any time here. Been here, done this.
I’d get a real shower stall with lots of room to move around in. We currently have a narrow claw foot tub with shower curtains all around. It’s a too much like trying to get clean while wearing a raincoat for my taste.
I’ve thought of that, but I would have a base home, and then I’d rent an apartment for 6-12 months in various cities I wanted to explore. Rent a place for 6 months in San Francisco, then rent for 6 months in Seoul, 6 months in Berlin, etc. etc.
Pay off bills - I dream about what it would feel like to sit down with my checkbook and start writing checks and know that the debts are all paid. I’d feel so light that I’d probably float away.
Buy my daughter and her family a house or pay the mortgage on the one they have and buy them new, reliable cars. Put money away for all of the grandkids’ college expenses.
Buy a vacation home somewhere warm and quiet.
Travel - go to Italy and spend as much time as I want exploring the area where my grandparents were born.
Donate money to our local animal shelter and zoo. I would specify the money has to go directly to the animals’ care and not administration.
I wouldn’t need mansions, expensive cars, jewelry, clothing, etc. I would just want to live without worry.
I don’t have a gazillion, but since I started making more money I’ve decided not to care about the cost of dry cleaning or even hotel laundry services. We have a dry cleaner that picks up and drops off at my office. It’s not cheap, but incredibly convenient. I would say the same about the the high priced hotel laundry during long trips. So nice.
I’d go mad and buy a bottle of Sauternes for Xmas*. Maybe one for new year, too!
j
Buy a house and pay off the car.
Then set up a private foundation and donate the majority of my gazillions to it and spend the rest of my life as a philanthropist.
An old pick-up truck to have around for the odd times I want to tow something. Yeah, I can rent one and I do - its cheaper than the insurance, upkeep, and all that stuff. But having some nice comfortable $400 beater just sitting there ready to go is a small extravagance that would be way at the top of my list.
**** Breaking News ***** Internet Message Board sold for $1 bazillion dollars after strange bidding war erupts.
After tearing down my house and building another on the same land, I’d bankroll a really good film adaptation of The Stars My Destination. (That ought to make a lot of money go away quickly!). 
I first heard about this in relation to Jerry Lewis. This is apparently exactly what he did - wore them once and then had them laundered and periodically the accumulated bundle was donated to charity( homeless shelters or whatever ).
It’s an utterly hedonistic excess that appeals to me greatly. The donation relieves it of being too wasteful of an idea and man…there really is nothing better than a fresh pair of socks.
Pay down bills.
New cars for my husband and me - nothing extravagant; we have aging Honda cars and we could just get updated models of each.
Have our cleaning lady come in weekly vs every 2 weeks.
New hardwood floors throughout, installed by a professional.
If fact, almost everything from here on out would be installed/remodeled by a professional. I’m very handy, and we have done so much in our house ourselves, but it’s not something I love.
You want modest?
I would take a week off and give the house a thorough cleaning. It needs it. Top to bottom, run the vacuum and the carpet cleaner, clean the light fixtures, and swat random cobwebs. Don’t get me started on the cabinets!
I would buy my favorite soccer club just so I can fire the coach 
Buy a new tailored suit and some nice shoes.
Get lifetime memberships to various professional academic organizations. (These usually go for around $1,500.)
Buy lunch for the entire office. Then quit.
Subscribe to every newspaper that could be delivered to my address.