Sedona is in the middle of some beautiful red rock valleys and formations. The drive from Flagstaff to Sedona is quite fun when you have to drive through several miles of switchbacks down a cliff on Rt. 89A. After that point, you drive through Oak Creek Canyon, a very beautiful drive.
Coming from the south, get off of I-17 on rt. 179, and take that north to Sedona. It goes through some beautiful areas.
Once in Sedona, there are a lot of neat shops and restaurants. My father recommends that you take a jeep tour of the area. He went on a 2 hour tour, and when it was done, the group wished they had taken a longer tour.
For those that are even more adventurous, take 89A west of Sedona, through Jerome, and on to Prescott. Jerome is on a 7700 ft. high mountain, and the drive is quite exciting. Just watch out for the tour busses that have to stop and back up to make some of the hair-pin turns!