The best time to be in N.O. over the Carnival Season is the weekend prior to Mardi Gras. That's when all the partying happens. By Fat Tuesday (actually Mardi Gras Day) lots of us are already tired from 2 solid weeks of parades and parties.
I'm not sure what the date of Mardi Gras is this year...it moves around accodring to Lent. It's always the Tuesday before Lent.
Sometime in February 2004.....
Hotels: You've got some shopping to do.....If you're staying in the French Quarter be ready for madness 24 hours/day. To stay outside the Quarter is a good plan if you want a break from the festivites and crowds.
Good luck.
-Gene