My total student loan debt was much less that yours FWP. OP's balance is half of what yours was. All of his loans are at a higher rate than the loans I chose not to accelerate (but if I did have loans at 3.8% I'm uncertain how much I would accelerate repayment). I certainly agree that the flexibility student loans provide (defferment, forebearence, and income based repayment) is a double edged sword that lets some people do financially stupid things (take on way too much debt, let interest balloon the loan balance).
I like the advice of using this year with only part-year full-time earings to put some money in a Roth IRA. I'd also make sure to get any available 401k match. Some would argue that you should max all your tax advantaged savings before accellerating payment on a 6.3% student loan, but I agree with FWP's advice to accelerate this loan payment. Each time I paid off a loan, I'd reevaluate how accelerating pay off of the next highest rate loan fits into my overall financial picture. At some point, your increased work experience, reduced total loan balance, reduced minimum loan payment, and reduced aggregate interest rate will be sufficient that you feel confident in choosing to maximize your tax addvantaged savings over continuing to accelerating loan repayment.