In Ontario our break is the second week of March, and I've learned that that's also Texas' break, plus of course many places elsewhere.
We will be there that week next year because of a conference, but had decided to go a bit early to try to get a few less crowded park days in...but now that the crowd calendars are up I see that Mardi Gras is the first week of March next year, so crowds are forecast to be higher than typical for early March. We were there in February for Mardi Gras week this year, and it was largely crowd level 8-10, although a big part of that was South American tour groups and families. I would assume by March that the South American crowd falls off, although I don't know for sure?
At this point I'll be happy with any days under a 9, I think, but will also just plan for crowds.