Depends on whether you are looking for short (up to 5 years) or long term (5 years or more) returns. Both are good investment products depending on your need.
i believe there's also a tax advantage on the t-bills if you live in a state that taxes income.
Of course, I have liquid money in case of emergency - just had a new roof/gutters put in a few weeks ago. Can't lock it all up.
our liquid emergency funds are not kept in cds. we have 2 savings accounts we keep $500 each in b/c the credit union pays 7.19% on 'the first 5', the rest of the liquid e/r is in a money market (currently at 4.07%). i feel you on the big expenses-we just had to replace the hvac/heat pump

The next two, I asked if they could waive the penalty; I didn't even give a reason. Both banks agreed without a problem.
when i went to break a couple when another credit union was offering a much better rate my primary credit union asked if i was willing to let them try to match the offer for the remainder of the existing term. they could not but it was nice to learn this is a possibility.