First step: write an "investment policy statement" that will determine how much of your portfolio should be US stock, international stock, US bonds, international bonds, other assets. Different people have different risk tolerances and your investment policy statement should capture this for your situation.
I see little reason to invest in the non-Vanguard funds given that you have Vanguard Institutional class funds available. The Vanguard Institutional Index Fund is an S&P 500 index fund with a 0.02% expense ratio. You can do a lot worse than to use this fund to meet 100% of your domestic stock allocation. To mimic a total stock market index, buy the Vanguard Institutional Index, Mid-Cap Index, and Small-Cap index in an 80/10/10 ratio.
I'd get out of the "Stability of Principal" fund. That's code for cash equivalents, which is not what you want when you're looking for long-term growth.
The Vanguard Total Bond Market fund is fine for your domestic bond allocation.
Given that the international stock funds in your 401(k) are from higher-fee providers, you may wish to buy international funds in your IRA or another account instead of your 401(k).