Since you're expecting a new addition to your family soon (congratulations!), I would hold off on making any major money decisions until you know that everyone involved is healthy. You may have the best health insurance in the world that pays for 100% of every medical bill, but you don't know if you'll need time off work, additional equipment, etc. that have costs outside the realm of health care/health insurance.
That said, I would absolutely not take the money from the 401(k) to pay off the student loans. The tax penalty plus the lost opportunity for gains will be far higher than the 6.8% saved on the loans. However, you need to get those loans paid off! For the taxable account situation, look at it this way: "would you take out a loan at 6.8% so you can use that money to invest?" If not, why would you invest when you have loans at 6.8%? There are no penalties (except maybe a capital gains tax, if you're in the 25%+ tax bracket) for cashing out stock in a taxable account and using that money to pay off some or all of your loans.
But again, I personally would make sure everyone is healthy before spending all/most of your liquid funds on debt.