I will go to great lengths to earn miles/points, but with that amount of money interest rate is going to trump anything else.

Personally, if I had that amount of cash sitting around and I could bear a small amount of downside risk I'd be putting $100k of it in a muni CEF (http://www.dividenddetective.com/closed_end_funds.htm) that was trading at a discount to NAV. You should be able to find a yield of 6+% federal and state tax free in most states. Just to emphasize again munis are not without risk, but unless you are going to need the money in a hurry or you absolutely can't risk losing a dime of it then IMO munis are offering a great risk/reward compromise.