I'm definately one of the "cash poor" folks. I'm like a Fedex Driver - less than $20 cash.
I use credit cards all the time, practically everywhere. We use one exclusively for gas, because we get 5% rebate - why pay cash when card is cheaper and more convenient?
We use another credit card for most of our other "general" purchases and get 1% to 5% back depending on the items, locations, and if there are promotions for that month. We pay of our cards completely every month. We also have 2 other "back-up" cards that we don't use. We've had more than that, but canceled them because it's probably silly to have too many.
I will agree that you can spend too much with a card quickly - but it's just a matter of discipline. It is easier to be undisciplined with a card, because, as mentioned - with cash there's a "hard stop". But it's nice to have the card when you're on a trip and you have unexpected trouble (tire blowout, storm makes you stay an extra night, etc.) and you have the extra cushion already.
And I would echo the sentiment about "no power, no cards". We learned that during the ice storm last year - cash is king for that. We were fortunate that we had enough cash laying around until the banks could get back open (by generator power) to be able to get some more. Now as a rule, we keep a few hundred in cash around. Although, we noticed then too - having a $100 bill is almost like having no money - some places don't have enough to cash it out if you only buy $20 or so.
I also like seeing the itemized statement on my cards - that way I know at least where I spent my money and wonder if I really needed that monogramed tractor-radio cozy or not.
Good luck and take care.