I stash "cash" in a money market called SWVXX. This money is available in a day if needed. My checking account is with Schwab also, so it's very easy to shift funds to pay bills. The money I have in SWVXX is in my IRA so the tax issue is not relevant.
One of my goals when I retired was to get all my accounts in "one basket", which I managed. I have a Roth, an IRA, a brokerage account, and a checking account all with Schwab. My wife also has accounts there which I manage.