Stop contributing to my 401K/IRA after this year
I'd continue enough into the 401(k) to get the company match (assuming a reasonable vesting schedule). You might not even notice it, especially with all the company stock sales. Yes, you probably have enough in the 401(k), but for the little bit each year, I think it's best to take the semi-free money.
Have you already consolidated old 401(k)s, if any?
Start selling Company Stock
Vanguard it up - specifically, VTI ETF - start building up VTI as my main fund
I'd suggest using VTSAX - their Admiral shares of the same fund - instead of the ETF. Frankly, I find ETFs to be a pain in the ass, and when you have more than $10,000 in a Vanguard index fund, there's no advantage to the ETF over the mutual fund itself.
I'd also suggest VTIAX - their international index - for some added diversity; maybe make this 20% of your stock holdings.
You might want to consider some bonds, but it's a mixed question whether or not to get tax-favored bonds (whether federal or state, depending on where you live). You'll have a high income for a few years, especially with the company stock sales' capital gains. What bracket do you expect to be in during semi-retirement?
But beyond that, I'd say you're fine.
I'd avoid wrap funds in taxable - such as target date funds. A combination of their re-balancing and non-tax-favored bonds are problematic for your taxes.
Important decision for you: are you going to treat your taxable, which has to last you 42 until at least 59.5, as a separate account from your tax-advantaged accounts (401(k) and IRAs) for purposes of asset allocation?