We live just a bit north of the North Rim. It will still definitely be closed then. The North Rim is much prettier than the South Rim. The weather here will be about in the 50-60's in March during the day, but will be in the 30-40's at night. Days will probably be clear, with occasional storms, but storms don't last long when they come in March. Zions canyon is also about here, and is open and beautiful all the time.
The sky walk is stupid. Quite a waste of time and $$. The road is not paved, and it's not much there. Cross that off your list. It's at the end of the canyon, and isn't even very pretty from down below (we went on a river trip through the grand canyon 2 years ago - what a blast!)
I'd love to give you more ideas about what is in this area.