1 week.
Depends.
DH was staying in NY near Niagara Falls for work. At 5 pm I got the idea to pack the kids in the car and go visit him and the falls for the weekend!! It took 8 hours but it was fantastic!! =D
Depending on how long of a road trip. For a weekend camping trip I plan for about a week. A road trip I would say about a month of planning.