The Grand Canyon is about 277 miles long and up to a mile deep, and almost every photo of it lies a little, because nothing gives you the scale. The rock at the bottom is nearly two billion years old. The Colorado River cut the gorge in a few million, and on the South Rim you stand on the edge and look at all of it at once. About 115 miles south of it, Sedona sits among red sandstone buttes that glow orange at sunrise and sunset, and the town between them, Flagstaff, is the place where Pluto was found and where the sky is dark on purpose.
This is a driving trip, and it is not a city guide: the distances are the point. Five days is the right length because the canyon deserves two of them, one to look and one to walk a short way down, and Sedona and Flagstaff need a day each to be more than a drive-through. Add a last day on the road home through two volcanic national monuments and you have the whole Colorado Plateau in miniature, without a rush. Be honest about the season, too. The rim is cool and often snowy in winter, the inner canyon is dangerously hot from May to September, and Sedona is best at dawn in summer.
The days run Sedona, then Flagstaff, then two days on the South Rim, then the loop back through Wupatki and Sunset Crater. Start on a Thursday: the Sedona trailhead shuttles usually run Thursday to Sunday, Lowell Observatory is closed Tuesdays and open on the Friday this order puts it on, and the canyon days land on a weekend, so book Tusayan early. Flying into Phoenix is the easy start. If you arrive from Las Vegas, which is about 275 miles from the South Rim, read the 3 Days in Las Vegas guide for the city, then run this plan backwards, starting with the canyon. More about the country is on the United States page.