Sedona is somewhat of a tourist trap in regards to the shopping there. However, if you're into hiking, biking, or off-roading there are some great trails there. Oak creek has lots of nice hiking too. I live in Flagstaff and we go there every couple of weeks in the winter time to go hiking in the warmth. Sedona is about 20 degrees warmer than Flagstaff. The only place we go eat in Sedona is at the airport. They have all you can eat King Crab on Thursday nights for about $26. Here's the website:
http://www.sedonaairportrestaurant.com/

Highway 89 is a great drive - we take it down to Phoenix when we're not in any sort of hurry.

Definitely bring a jacket if you're going to do downtown Flag at night. The lows are already in the low 20's.