Are treasury bills a good investment?

Treasury bills: securities offered by the US Treasury with a maximum maturity of 180 days.Treasury Notes: securities offered by the US Treasury with a maturity of 1 year to 10 years.Treasury Bonds: securities offered by the US Treasury with normal maturities out to 20 years.
All fixed income returns are driven by the yields on Treasuries, usually the 10 year maturity from the date of comparison. The returns over and above the Treasury rate are a valuation of risk in the underlying investment by the market place. The higher the return, the greater the implied risk. Ask any holder of Puerto Rico municipal securities who bought the higher yield than he/she could get from US muni's.
Using those basics, you can get a better, ten year return than Treasury's, but you have reinvestment risk. One of the terms given you when you purchase any fixed income security is Yield to Maturity (YTM). YTM takes the price of the bond AND the reinvestment of interest received reinvested at the rate that exists on the day the security is purchased. If rates move at all between purchase date and maturity, the YTM is inaccurate. It is only good at the time of purchase and should be used for comparison purposes only. If you look at government securities from overseas, they may pay more in interest than US Government's but you have the risk of currency fluctuations among the countries involved in your transaction.
Having been involved in the US markets for 40+ years, what will get you through this crisis (and the next one that comes) is prudence. Prudence in setting up a strategy to cope with the variables and prudence managing your affairs or prudence in selecting someone who can help you manage your investments. I don't think there are any magical solutions or single answers. And, please pardon my initial "preachiness". It was meant to teach, not correct the question.