When you ask "What is the best way for a guy like me to accumulate wealth by investing over a 10 to 20 year term?" are you referring to Vanguard investments, or investments in general?
If your goal is early retirement, then obviously you're going to need access to investments (or the cash flow from those investments) in the intermediate years when you can't access your tax advantaged accounts (or social security). I know... there are some strategies for accessing these funds early but let's set those aside for the moment.
It seems the favorite investments for the ER crowd include taxable Vanguard funds, dividend stocks, and real estate. My personal choice is Vanguard and residential / commercial real estate, but that's me. There are a lot of resources out there on each of these classes.
If you've maxed out your retirement accounts and just wish to plow more money into Vanguard, I might suggest reading "Gone Fishin Portfolio" in addition to JL's blog - the book strongly pushes Vanguard funds, and lays out an allocation methodology slightly more complicated than JL's. I found some of that useful, but there's nothing wrong with steering towards Jim Collins simple approach. Still, an educational read if you're just starting out.
Finally, you may also want to consider Betterment for your taxable accounts if you want to keep things simple and let them worry about allocation