the only time i carry cash is if im going out of town, if im going to a place i know that im going to be tipping a lot (bars, concerts, sporting events), or places i know that dont except cards. its not that hard to figure it out ahead of time whether or not you're going to need cash. otherwise, its all cards for me. i dont even have a real wallet, its juts a small card holder.
the thing i hate is atms that charge you fees for withdrawals. theres is no way in hell im paying a fee for money that is mine.