If you're looking to stay in Marigny, I can't imagine a better place than Kate's. It's a block away from Mardi Gras Zone (where you can do pretty much any grocery shopping you need), blocks away from some of the best restaurants and bars in Marigny and Bywater, and a hop, skip, and a jump to Frenchman St.
The place itself is fun and funky, and has a great eclectic vibe. It was so warm and welcoming, I found myself wanting to just hang out there, even when one of the best cities in the world was right out the front door. My only complaint is I wish I could have stayed there longer!