Looks like you are going to be near the Flagstaff/Sedona area. Some suggestions.
- We loved that town - There is a central shopping/eating area where you can sit outside and eat at a couple of cafe's. Worth a stop to eat and walk around for an hour.
- If you haven't been then you need to go. I have only been to the South Rim - As you are coming down from the north you should consider the North Rim - I hear it's spectacular, but not a trivial thing to get there.
- You should go to see the scenery. There are a few vistas that are visually stunning and made me stop the car, like coming down the hill toward the main intersection. Interesting place, though - all the stores close at 6pm, so when it's cool enough to walk the streets nothing's open.
- Frank Lloyd Wright designed a church nearby - stop and see it - a beautiful place.
- Driving the canyon between Sedona & Flagstaff will be great in the SLK. I think you gain 3,000 feet in 30 minutes. Remember - altitude changes temperature - Flagstaff can be 25 degrees cooler than Sedona - we just don't get that back east.
- Enchantment Resort - About 20 minutes west of Sedona - Posh place where the rich folks vacation - Great place to have breakfast out on the patio - it won't break the bank to do that. You may need a reservation.
- Jerome - We loved this little town. An old mining town on the side of a mountain about 30 minutes SW from Sedona. A one street town - it winds back and forth up the hill. Lots of art shops, souvenier stores, and restaurants. You should stop for lunch or dinner. When we were there they were having an art festival - all of the shops were serving wine and cheese.
Regardless - Enjoy your trip. We love the American West - it is absolutely beautiful. Most of the places we have been are west of your route, but if you have a chance to go farther west another time then you won't regret it.
In the interest of balanced reporting - it is also a pretty desolate place. If they say there are no gas stations - then they mean it! I was planning on visiting Chloride, Arizona on the way from Sedona to Vegas via route 93. After driving for an hour through absolutely nothing I decided that if my rental car decided to conk out over the hill in Chloride then it would be weeks before anyone found me. Thus I concluded that if you looked in the dictionary under "Godforsaken" you'e see a picture of Chloride, Arizona.
Enjoy your trip and take lots of pictures !