Credits cards, especially Visa and Master Card are widely accepted at restaurants, ounges, bars, and shops.

It is becoming increasingly rare to find a place serving food that does NOT accept credit cards.

If you need cash, then simply get cash at either the ubiquitous ATMs or cash back after purchase of food items at a grocery store.

In the last couple of decades of travel to all parts of the U.S., I've never carried more than $100 in cash at any one time. I either pay with a credit card or I just get cash as noted above.

There are a few restaurants that do not take CC - so ask when you make reservations - but this is VERY rare. Assume you need to pay cash for small items - $10 and less.

Definitely use the ATM to get some cash - no need to bring lots with you. It is risky to carry a lot of cash and you pretty much always get a better exchange rate though the ATM than exchanging currency. Another consideration - if you are planning to exchange currency, you will have to do it at the airport or at a larger bank - not all banks do currency exchange and exchange offices are rare.

In rural areas you will find more places that don't take credit cards than in cities. In New Orleans specifically there are a fair number of places that don't take cards - more than you would expect in a city. Some places are just sort of old school about that.

I can't think of a place that doesn't take credit cards, especially a bar or restaurant. Especially if they are a legit business that is.

I believe Johnny's Po-Boys is cash-only. Definitely a legit business and definitely a must-eat in New Orleans.

a good rule of thumb is to leave home with everything you need. never anticipate that something you will need later will be readily available at your destination upon getting there.

i was once, almost, burned by an atm in a different state because i couldnt withdrawal funds being that the atm didnt take my card indicating it was out of their network. my only saving grace out of the dilemma was using my credit card. if i didnt have a credit card then, i wouldve been in dire straits.

The post above would seem to have you carrying a lot of cash, and I don't believe it is good advice. If that particular ATM was not his network, there are others that would be or it would be a very isolated area.
There are a few places in various cities that might be cash only--little "hole in the wall" kinds of places (good food, but maybe quirky).
Use ATMs and credit cards.