It's an odd tip to make about a place, but if you blink, you might miss the heart of Sedona. Part of this is probably due to the road works which have made a real mess of the place and most of your concentration does seem to be devoted to the fact that you're trying to see exactly where on the road you should go.
And quite obviously, any attention that is left will almost certainly be focused on the red rock hills surrounding you.
However - in all this distraction, it can be surprisingly easy to miss the best bits of Sedona, if you've never been there before.
Driving in on Interstate 17 from Phoenix, you will drive through some beautiful areas, stucco housing and roadside vendors selling super hot sauces, local vegetables and even old fashioned Sasparilla. (Don't be surprised if you end up chatting a while with one of these vendors, they have a lot they like to tell you about the area...)
Just beyond this heading in towards Sedona begins the road works, and you will have to juggle with this some to get to some of the first local jewelery stores and art galleries that are positioned right on the road. Some of these are excellent, so it's a good idea to park your car at one and sprint across when there is no traffic to the others - finding your way into each one can be a nightmare. (This is based on the condition of the roads from early 2009 - hopefully by the time you're trip is planned it will have been largely cleaned up.)
Yet - after this - it can be very easy to make the turn onto the 89A and head out of town altogether and never spot the best bits. To be perfectly honest, on our first tour around the town we spent a good bit of the day driving around the bigger, more built up areas of Sedona before we doubled back and happened upon the bit we had been looking for all along.
And though most of Sedona is pretty nice to look at, it would be a crying shame to visit the city and not see it's most incredible area. So be sure (if you've not already mapped out your path) to stop in at a local shop, tourist center, or speak to one of the vendors on the road side about how to get to the old town art and gallery area of town.
Once you're there - you won't want to leave. Having not allowed enough time for my own Sedona visit, I highly recommend you allow no less than two full days of exploring. Pass through it if that's all you can have time for - but I guarantee you'll wish you had more time and vow you'll have to come back for another separate visit.
I would suggest you allow no less than one full day of walking around the town center enjoying the shops, art galleries, amazing restaurants and cafes - and one full day of sight seeing the desert and natural vistas around you. (Not counting for time to get to and from)
If you are particularly interested in one area over another - allow even more time. You'll be surprised at how very much there is to see and do in this little corner of Arizona - and it's a pretty easy drive to other nearby attractions as well, on the very unlikely chance you do all you want there and still have time to spare.
The town center itself was one of my favorite parts. Decorated for Christmas in a way you'll only experience in the south west - you could spend days and days wandering about the stucco buildings and little alcoves, all filled with stunning and unique galleries, shops, eateries and cafes. To date it's one of my favorite little towns, and I highly recommend you spend a bit of time indulging in it while in Arizona.