I think it's important to set up the ladder so that the CDs mature (into cash flow) at a pace that covers your cash flow needs. That way, you avoid having to redeem them early. Nonredeemable CDs get better rates. So, for example, if you have $100K to invest, and you will need <$20K in a year's time and every year thereafter, it makes sense to put $20K in each of 5 CDs with terms of 1,2,3,4 and 5 years. If you need up to $10K every 6 months, you might want a ladder of 10 CDs that mature at 6 month intervals.
If the amount you want to invest exceeds FDIC guarantees, you may want to split your CDs between several banks. That us a lot more work, which a CD broker will do for you at a price. I investigated them a few years ago and found that their rates were significantly lower than what I could get at a bank. With a brokered CD, if you have to redeem early, you will have to find someone to buy it, and it might be a hard sell if interest rates have gone up in the meantime, so you might end up selling it at a discount. Another reason to avoid redeeming early!
My bank has been very helpful in setting up my ladders as they will get the best rates from competing institutions.
