Purchase $30K in I bonds and $15K in Patriot bonds on mileage earning credit cards before the 25th of May. You can redeem them on October 1st. You will forfeit 3 months interest, but the residual interest earnings will be competitive with what you would earn in a certificate during these approx. 130 days. During this time, try to do research on what your investment options are, without regard to earning miles.