If you buy bonds in a taxable account, you'll owe ordinary income tax on the bond income. That's true even if the bonds are inside a fund, like VBIAX . Given your HCOL area, max 401(k), and an extra $18k/year I'm going to assume your tax rate is high enough to consider tax-exempt bonds. Vanguard has state-specific tax-exempt bond funds for CA and NY, for example.
VBIAX only holds U.S. equities - no international. While there's an argument that U.S. companies do half their business overseas, sometimes international beats U.S. performance. You might want to diversify, even if it's just 20%.
How about something like this?
60% Vanguard Total Stock Market ("VTI", expense raito 0.03%/year)
20% Vanguard Total International ("VXUS", expense ratio 0.09%/year)
20% Vanguard Tax-Exempt Bond ("VTEB", expense ratio 0.08%/year)
I like ETFs, but you could do the same with mutual funds if you prefer. The key thing is to have an aggressive allocation to equities when you have an indefinite time frame, and as the goal of that money becomes clear, shift towards bonds/cash. If you know you're buying a house 2 years from now, you should shift almost all of it out of equities.
(In theory, 10% stocks and 90% bonds is actually less volatile than 100% bonds because of how stocks and bonds tend to perform differently).
You could also look at target date funds to see how as retirement approaches, the funds go more into bonds.