+ Depends on how many kids you ideally want.
+ Depends on where you WANT to live when you have kids
+ Depends on what your profession is (e.g. full-stack developer or business guy with niche skillset)
+ What's a reasonable amount of risk to you?

If you are a developer who can just go get another 100k job wherever then you can take a decent amount of risk (even running your own startup and failing).

If you live in a city like SF or NY and want 2-3 kids, that money can go VERY fast if you haven't planned well (should be looking into tax-free contribution trusts for the kids though.)

There's couple of things you can do:
1) Invest in assets (real estate, stocks, startups, muni bonds)
2) Invest in yourself (additional schooling or education)
3) Take a gamble and be an entrepreneur
4) Do NOTHING and keep your powder dry
5) Do a combination of the above

Interestingly enough, I think under the right scenario, you can learn to invest across assets & start a startup.

I do not recommend investing in startups until you've gone through a startup and fully realize how hard it is to succeed what kind of "real risks" you are taking investing in these companies. Plus, seed investing (what you will be doing) needs enough sample size - most likely min 20k @ 20+ investments and each having a chance to all go to 0 (very high chance; that's why a lot of crappy incubators flop).

Investing in stocks, bonds, real estate, etc. --> this can take thousands of hours to do well but you have to start somewhere in your life. B-school won't help you, getting a CFA won't help you, investing in these assets also means understanding the style of investing you're comfortable with. It's also a lot harder than people think it is at this point of the economic cycle (its was easy to make money when we were at the bottom of the market and fed juiced the markets up)... it's much harder to get good returns around this year to next year. However this also means you may want to play with tranches of 50k and give yourself 3ins to fk up completely. spending 150k total max loss out of 500k to put yourself into a position to force yourself to learn to invest is, in my opinion, a pretty cool position to be in, given that you still have a lot of dry powder left. That allows you to experiment with etfs, individual stocks options, futures, even day trading --> all of which even if you lose 150k over the next 2 years, it will help you see how that side of the world works for the rest of your life. And if it's the case that you're going to be fairly well off one way or another (upper-middle class lifestyle in your 40s), you're going to have to learn how to invest anyway.
Real estate investing in these times is something I would stay away from (if you're going to do it, I would spend money on getting some education on real estate and wait for things to pop in a few years or only buy extremely selective assets - just remember that being a landlord is a lot more painful than people realize in the beginning).

Becoming an entrepreneur - You're in a lucky position to self-fund the seed amount and especially if you're a developer then that seed amount can go a long ways. If not, you still have the financial wherewithdal to pay for a top developer for about a year. Even then though I would put a cap on it for $250k of your own money ($100k in developer expense for a year, $100k marketing expense, and $50k in living expense. Based on my experience, if you can't get enough "smart" money funding after you've spent $250k, that's probably not going to be a good idea b/c what you realize is that there's actually a lot of dumb "smart" money that just has to put capital to work.

All in all, I would focus on your passion (what interests you the most) and stick to one thing as the primary way to improve your financial stability and as a little hobby on the side, dabble in one more thing that you'd like to do better. (e.g. Do a startup and on the side invest a $50k allocation by following stocks in your startups' space).

One thing I highly recommend you to think about as a possibility is to spend 50k (10%) and travel around the world for 3 months with your wife. That can help in almost everything that you possibly want to do (even raising a family) : )

You'll have enough time to read about a number of things you want to potentially experiment with while seeing how the world is actually working and what each place needs; meet some cool people along the way and see how those people are thinking about the world. Plus, a decent amount of time to relax with your wife and have many a nights'conversations as to what you guys think is the right next step to take (under a stress free environment). Also, if you're going down the startup path - you're probably not going to take any time off your first 24 months and it'll most likely be the most stressful thing you've ever done...

My background:
I positioned my life to be single, no mortgage, work my ass off to save couple hundred thousand bucks saved by 27. Would like to think of myself as having domain expertise in finanical markets. For the past few years, continued to invest in public markets, decided that B-school was not worth it for me (have tons of friends who went to top b-school), worked & failed in my startup with my best friend, and wasted $150k of my savings. The best thing for my career was failing at my startup - I learned more than any of my friends who spent the same amount of money going to a top bschool. Better yet, I realized that even after I failed, that is the space I want to be in and that I'm actually pretty good at it (just didn't have the right business concept). Now I'm working with another startup. Prior to startups, I've traveled to over 30 countries over 6 month period and read every periodical / book / website on business, investing, startups, etc. Absolutely one of the best/coolest things I've ever done that provides dividends time and time again.

Can have a more personal chat if you think that I can help.