I would recommend you flip these allocations. You've got 90% in small caps and 10% in large caps (S&P)! That is incredibly risky, even riskier than the 100% stocks allocation that some people discuss doing (that 100% stocks usually means 100% VTSAX, which is mostly large caps, and some medium and small caps).
And don't limit yourself to Vanguard index funds in a 401k. List out all index funds and their expense ratios and pick from those.