Allow time to get to your destination and still have fun when you get there. Call whatever agency you need to get advance information, too. The State Highway Patrol, National Park, or local Chamber of Commerce are good sources of info. How many people are going. Well, it's back to that topic again.
People equate to supplies which further equates to weight.
It looks like we are moving every time we go camping. Or I think it does. Unless you are very careful, you will be unable to carry the supplies necessary for the trek if many people are going. It's no fun dragging tons of junk around. If you have to take a crowd, make everyone tote their share of the stuff.