Definitely recommend Ruby Slipper Cafe for breakfast. They have multiple locations. They had amazing eggs benedict (and very different than typical ones) while my daughter had pancakes that were the best I have ever tried. If you go, make sure to get on their wait list online because they can get busy.
Also, I don't know if you are flying in, but we had a later flight after our cruise. There is a an organization called Advance Check-in at the port that will take your bags to the airport for you so that you can explore the city more. We had tickets to Mardi Gras World which was within easy walking distance of the port on the same street. Afterwards, Mardi Gras World had a free shuttle to downtown that we took. Then we took an Uber to the airport where we met the Advance Check-in staff that had our luggage in a truck. It really made things easy.
Even if you don't have a late flight, Mardi Gras World would be a fun thing to do with kids before the cruise.