A.G.
If you take your car you are paying up to $25+/day for just hotel parking, not to mention parking fees if you drive anywhere like a museum or park, and you're taking a risk that enough valets will be available to get your car within 15mins of when you need to leave.
Take a taxi. Its $7-10 anywhere between the quarter, the business district, the warehouse district (there's some good eating there!), and the garden district. Plus if you get a good driver, he's most likely an old timer and can tell you stories about NO.
Try Hampton Inn (St. Charles), Country Inn and Suites (Magazine), or even Holiday Inn in the business district. All are business class hotels that usually provide bfast that should provide you some pretty good rates and are clean, not run down.
If you are looking for a cheap hotel within walking distance, try one of the hotels/motels further down canal, which is just a 5-10 min extra walk from everything.
How long are you staying? Here's a sample itinerary for the garden district:
Day 1 - Garden District - go window shopping, check out the old grand homes, have a nice lunch, walk through Tulane, Audubon and even the zoo, dinner at Commander's Palace.
There's so much to do in NO!