You both like travel, so I’d suggest using it as an “excuse” to fly only first class on any future travel.
And you both like food, so maybe a fund to support regular “over-the-top” dining experiences, a destination cooking class, new pans or appliances…
Other than that, I’d focus on one “purchase” or “experience” that would really last a long time. Some really cool $15k trip. Or maybe a piece of art for the home/garden.
Fly first class to Australia.
I’ve never done it, but by all accounts getting to Australia is a massive pain in the ass since you have to fly for approximately 200,000 hours. However, if you’re in the first-est of first class and can fly your hours in your own private seat-that-turns-into-a-bed both ways and still have money left over for an awesome vacation scuba diving in the Great Barrier Reef…then it sounds positively amazing.
Damn; you’re making this tough! That and I usually don’t keep the hookers on a table but -------- to each their own. 
I would go with something hobby-related if appropriate. Big spree at the book store, some fishing tackle I’ve always wanted, or something like that for at least some of it – say a couple grand. I was in a not-totally-different spot about 40 years back and had a spree of fly-tying materials and tools which I’m still using; stuff of such quality that I couldn’t really justify for myself. Its a nice reminder of the windfall every time I sit down and look at the vise.
Totally this. Not Paris for me (too close by) but certainly a lavish trip - possessions never trump memories in my book. For my honeymoon I flew business class from London-San Francisco, and did a tour around Northern California in two weeks, staying in some gorgeous hotels and eating lavishly. Easily spent the equivalent of about $12,000 I reckon.
Then with the remainder, I’d buy something that we can enjoy at home and remind us of our benefactor. My father in law died a few years ago and one of the things we bought with our inheritance was a woodburning stove - might not seem much, but on a cold winter’s night with a glass of wine, we frequently do a ‘Thanks Mike’ toast.
Lunch at Heavenly Valley. I’d cover the tip out-of-pocket.
To elaborate: A 21-day cruise from Los Angeles to New York via the Panama Canal. The rates start at $1449 a person, so you have plenty of money to upgrade that cabin and still have plenty of money to sight-see with.
Well, you’ve eliminated all the common-sense items like paying off debt or saving. You’ve eliminated the easy answer to spend it going on a trip somewhere you really want to go but seems out of reach. You seem happy with your cars and you won’t consider home renovations.
So I suggest becoming a patron of the arts. Find a film project on Kickstarter that you want to see made with a group that looks like they can pull off the job. Contribute at the “Executive Producer” level, which usually gives you things like a day of filming on set and the right to go to the premier party. You’ll get your name at the end credits and on IMDB for some some mediocre but hopefully interesting film. You’ll have the DVD as a souvenir and, if the director or stars make something of themselves, you’ll be forever able to say when they come up in conversation, “I produced their first film.”
Pay it off now. There has been a big cultural change: a few decades ago it made people feel great to own their house “free and clear”, and they had mortgage burning parties. [Nowadays most people look at mortgages in terms of minimizing taxes.]
there is a company called Kiva https://www.kiva.org/ where you can give microloans in combination with others. an example is a man in El Salvador needs $300 to buy supplies to make hammocks reviving local handicrafts in his area. They apparently have a good payback results.
Travel - do it now while you’re physically capable of doing what you want. We’re busy skiing, hiking, rafting, and biking now while we can push ourselves. Later we can spend time on a beach or visit the sights of Europe.
Bike trip through Tuscany with cooking lessons and wine tastings. Kiva is also a great idea; or how about volunteering to help someone else in need. Failing that, Set up a trust and have the interest fund a scholarship based on whatever you think is important. Even a $500 scholarship pays for a couple of books for a student who may need it.
The only time I’ve every gotten an “inheritance” was when my grandfather passed away. I used it to buy a sword.
So, a sword.
For the travel and animal interests on both your lists, why not an extended eco-tour of Central and/or South America? I would nominate Costa Rica, personally. A week spent in each of 4 of the more ecologically interesting (to you) regions with eco tours and animal observation/interactions sounds like heaven to me.
A Yamaha Disklavier piano. Since I don’t play piano, this would be a completely frivolous purchase for me. But if you play piano, all the better.
I would also consider artwork of some sort, a piece that you really like.
In my limited experience, CR is spread out enough and the roads bad enough that you can eat up a bunch of time travelling from one place to another.
We spent a week going from Arenal to Montevideo to Manuel Antonio, and I thought that a bit rushed.
Uh, just checked the prices of the player piano. I change my answer to artwork.
Unless a few more relatives pass away. Then the piano is back in consideration.
I would recommend to do something very memorable with the money so that you’ll always think fondly of his mom. Either go on a 1st class trip or buy something which you will have for a lifetime. That way you’ll always have the memory of his mom and her contribution when you think back on the purchase. Essentially, do something that you’ll think of like his mom bought it for you.
One expensive dream trip I’ve had is to do one of those Canadian train trips. They have luxury trains with glass ceilings and you can see amazing views in 1st class comfort. Different trips will be of different lengths and have different price points. It’s unique and you’d remember it forever.
That’s about what Mrs. R and I spent on a trip to Egypt, Kenya, and Tanzania a year or so ago. We just walked into a travel agent and asked her to make it happen. Very low-stress trip; saw stuff I’ll always remember. An elephant herd is silent, you know; except for the sounds of them ripping up grass to eat.
I’d buy a Bobcat. (The machine not the animal)
Three words: Guitar Acquisition Syndrome.
Oh, and some lessons. 