What would you do with $500k?

[Christopher Dowling]

I came to BP to learn how to buy multifamily property at a discount to either fix and flip (a la Nickerson) or hold for cash flow.
Obviously, BP is a vast, deep resource of knowledge and I have since been introduced to quite a few ways to allocate my capital. I would like to choose one avenue, learn as much as I can, and specialize in it over the mid- to long-term. Which leads me to my question: if you had $500k that you wanted to grow into, say, $2m as quickly as possible what would you do with it?
Some opportunities I am exploring:
Standard residential, self-managed
Commercial multifamily
Mobile home parks
Commercial (retail, etc)
Land and farm
SFR notes, NPN or otherwise
Commercial notes
Tax lein
Other?
My wife and I have excellent credit and look to use leverage to maximize our returns.

Thanks for your help.