It's all well and good to say that it's not worth going to 4 corners because you've been there and there's nothing to see. They haven't been there and mebbee want to say they've been there, done that.
Personally I'd hit Las Vegas and head up I-15 to St George and Zion, Bryce Canyon, Capital Reef, Goblin Valley, part of City Slickers II was filmed there, and then Natural Bridges. From there you could head for Blanding, Hovenweep N.M. and then 4 corners and Ship rock. Opitional from there,would be to head down to Chaco and down to I-40 and back to Vegas or Chaco and Canyon D'chelly (sp?),Monument Valley,south rim Grand Canyon and back to Vegas. If you are pulling a toad, I would highly recomend the trip into Chaco and if not, it can get REALLY washboardy as it's gravel and dirt most of the way.
I love that part of the country and have been to Ghost Ranch,out side of Abiquiu about ten times since 1958 from the puget sound area every time. The first two times was with our family of seven in a '55 DeSoto sedan and we tent camped a lot of places along the way.
Have a good trip and drive safe.