Three words, Balanced. Mutual. Fund.
Seriously mate, a C.D. will NOT cut it, I don't know how old you are, but if you have 30 years to let it sit, even at 7% interest (very low for a balanced fund, more like 10%) it will net you well more than enough to live comfortably when you retire. Just remember, plan to live to 120, plan for at least 5% inflation, plan for at least 120% your current monthly income (inflation adjusted, of course).
Oh, and if you decide to go with a professional to handle it for you, try to get a good class A balanced mutual fund. yes you have to pay a fee up front, but in the long term it is more profitable for you.
Oh, and don't forget to have your dividends and capital gains reinvested, it doesn't work nearly as well unless you do.
Good luck, and cheers on such a nice signing bonus!