But even if I end up with 1% less interest on an average of $20,000, and I think it's really a lot less, I'm willing to take the lower yield for the added convenience.

We keep more than "necessary" in our checking account both for convenience and to reduce risk. Risk of what? Of screwing up. We pay off our credit cards every month and haven't bounced a check in I don't know how long. To maximize interest, we kept the minimum in our checking account. One month, DW and I got our signals crossed and transferred out some funds that should have stayed in our account. Checks bounced, interest charges hit, fees were levied. It wasn't pretty. I was astounded at how expensive it was, and wonder about the people who bounce checks on a regular basis. In only a few days we lost the interest saved over many months of continually moving funds around.