Here's what I'd do: Assuming the new loan is at less than 6.8%, pay off the SLs at that rate, keep the ones at 2.75%, put whatever down payment you need to not have PMI, and if there's any left after the down payment and paying off the 6.8% loans, invest the rest or put it as more down, depending on the interest rate of the new mortgage (most likely the former, based on today's rates).