First off, congratulations on getting mostly debt free and having so much extra!
That said, even though $700 extra sounds like a lot, it isn't. You already have a 1 year emergency fund, so that's good, which wipes out my first suggestion. You also wiped out my next suggestion, which is looking at improvements to your house, such as appliances or other renovations.
So my next suggestion is putting some of it into the mortgage. (I say some, because I have other suggestions.) The faster you pay off the house, the less interest you pay and the sooner your payments go away, plus your credit rating goes up. But that's all covered in other Answers.
What none of them (so far) cover is: have some fun! I'm not saying to blow all of it on extraneous BS, but I am saying to invest in your mental health by not working yourself to death without any playtime.
Take time to be with your kids, your family. Take your spouse out on dates, even expensive ones. If there's anything you've wanted since you were a kid, like you would kill to have it, go buy it (not actually kill for it). Start a collection of things you enjoy. If you don't already have one (or several), start a hobby. Ok, so I'd stay away from the expensive ones, like motorbikes, boats, cars, and several others, but there's quite a few hobbies that don't take all your time and money.
Do you like to travel or go on cruises? Do it. And feel free to get some souvenirs. Do you or your spouse like jewelry? Get some (more).
You have already satisfied your basic and quite a few other "advanced" needs for yourself and your family, so go back and satisfy some basic needs that so many people with money (and on this forum) forget about. This life isn't just all about money. You don't have to spend all of your money this way, but you should be able to enjoy it, instead of worry about it, even the extra that isn't required for your survival.
Money is a tool, so use it as a tool, instead of it using you. You are in the position to make that happen. Some people try to do this with stocks and bonds, but what they are just doing is changing their worries to "am I going to lose my money when the stock market fails", because it will. It failed early last year, but then recovered, which "proves" to some people that stocks are safe. They aren't, but some people will gamble regardless of the reality of how often they lose.
Sure, you are already into stocks and bonds with your retirement funds. Those are generally extremely tightly managed, so you shouldn't have a problem there, unless the CEO of your company drains all the accounts, like what happened with my mother, and even I'll admit that's a pretty low possibility. But going outside the "retirement fund" area of investing can get real tricky very quickly. I'm sure I'll get some arguments in the comment for saying all that, but whatever. Far more people lose their money than make money in stocks. I'll just leave it at that.
You can also look at your neighborhood and surrounding community to see what needs help. Yes, you could donate more to your religious center, but I'm talking about parks, communal areas, homeless shelters, food pantries, and lots of other places that help the needy or the general area.
With the pandemic of 2020 and it continuing into this year, there are quite a few people in need. Even if they got hired again, millions of people lost their jobs last year. I'd wager that most of them are still suffering from months when they lacked income. Food pantries are still being overwhelmed with people needing food.
The $600 stimulus was great, but there are people still looking at eviction for months of back rent. Families with kids are probably looking at needing new clothes. One year in the same clothes for kids can become ragged or too small real quick, as I'm sure you know.
You might even consider giving your friends or family a boost. I had a friend that said had a negative bank account last month, so I have them money. I'm actually in a similar position as you, with making more money than I need to survive, but I just recently bought a house and did major repairs I had to get loans for, so not quite. However, I don't have any credit cards, student loans, and my car loan is low enough I could just pay it off, but my emergency fund isn't very high, so I'm not paying it off yet.
My car could also use some major repairs, but my friend needed the funds more than I did. I also (still) need to send some money to my mom, who suffered major losses in the derecho last year. She's retired and no longer physically able to work, and her insurance didn't quite cover everything, even with the help from her neighbors. My dad is working on packing up his house to move into a retirement community and is going to be sending me a collection of stuff we've spent over a decade putting together, so I need to send him some money for shipping and other expenses. He isn't expecting money, but I should do it anyway.
My point here is that you can get some mental ROI by helping others with your money. They may some day even help you if your situation ever turns around and you need money. It sounds like you have everything under control and covered, but that can unfortunately change quickly. The company you work for might get sued and they "throw you under the bus" for some reason. So instead of them taking the blame, you lose everything. There's probably a 1000 or more ways to lose everything, which is exactly when you need the help you gave to others. If you haven't already made deep, meaningful connections with people, now is the time to start.
Money just gets you on some people's radar, but if you are enthusiastic and actually mean to help people, and help them with some sweat equity as well, you'll make those bonds deeper than just your or their pocketbooks.
Not much extra
I said this earlier, but didn't explain it, so I'll do that now.
You aren't going to become a millionaire any time soon with just $700 extra a month. Sure, it's absolutely fantastic you have that much extra after doing all the other stuff you've already accomplished, but that's not "buy a BMW with cash" kind of money. You still need to make sure that you don't over spend.
Yes, I suggested spending lots of money, but in this section I'm going to remind you not to go completely off the rails and ruin your budget.
You've done a great things by paying off most of your debt, so you can loosen the purse strings some, but you can't let them go completely. Even when you are having fun, donating, or whatever, you still need to make sure you are doing it at least semi-responsibly. You don't want to get back to the point where you have to worry about money.
It might not seem like it, but you are still on the thin line between being completely financially stable and completely broke, like most people. Yes, you have a 1 year emergency fund, but what happens if you can't find another job in a year? I've had times where it took 12-18 months to find another job. My brother-in-law was in such a niche managerial job when his company downsized that it took him over 2 years to find a job. And he ended up taking a job in building maintenance. Evidently it pays their bills, and he likes it, so that's what he's doing. I'm sure they aren't as well off as they were, but that's not my decision.
Do your own thing
If you want to make yourself fully financially independent, you should start your own business. I've started a business on far less than $700 a month. Maybe that's why it's still a side gig after +6 years, but with your resources, you could make a real go of it. "All it takes is..." No, it takes a fair amount to get started and to keep going, but it's not as expensive as it used to be. Depending on what you do, you might use your current job as the basis of the business or you could pivot a hobby into a business.
Whatever it is, it needs to be something you could do for 60-80 hours a week for the next couple years to get it off the ground. At first, you don't want to do that much, as you'll still be working your current job to fund the business, but that $700 a month goes a long way to getting a domain name, website, advertising, equipment, and more. Maybe it's not you, but your spouse that starts this business. Maybe you go into business together. Some people will say this spells disaster, but many times it's the family business that works where an individual fails.
And you still don't have to spend all of that money on the business. You can still do the other things I suggested earlier. In fact, having fun is key to preventing burnout from working so much. I know I don't take enough time for myself.
There's a lot of things that you've done, which is a great accomplishment, but there's quite a few things you either haven't mentioned or aren't already doing that you could do. I didn't cover all of them, but I hope I offered some options you like.
Keep up the good work and I'm sure you'll get it figured out. The key thing to remember is that you don't have to "have it all figured out" now or at any other time. And you should remember that decisions you make now may not make sense later, so remember you have the freedom to change your mind at any time.
Good luck and have fun!