I guess the thing you need to consider pretty carefully is whether you'd like to lock money away where you can't get to it (CDs for example), OR whether you'd like your money parked somewhere where you can get at it pretty easily if you should want to (savings account).
Personally, I *do* like to lock money away, where I can't get to it. If I decided tomorrow that I wanted to impulse-buy something (say, a car), I simply wouldn't be able to access enough money to do it--there would be an inherent waiting period on any large purchases. (There are big advantages to this for me! But I can see that it has its disadvantages too from another point of view.)
If life is unpredictable enough for you to need real short-term access to your money (say, if you might be offered a job in the next year that would require buying plane tickets, or buying a car), then perhaps it is good to keep some of your money (say, $2,0000) in an out-of-the-way savings account, and only sock away part of the money.
As for CDs and getting a good return on your investment, I think there are many here who could steer you toward options that have better return without much more risk (mutual funds, etc.) But personally, being very risk-averse, I like CDs because they are just a step above keeping your money under your mattress. As time goes on, perhaps I will reconsider but for now, I like the security of it all.