We've done the trip twice in the last three years,and will be heading that way again in June. Last year we did the southern route (rt40 primarily) and hit snow in NM,Co,Wy and savage storms all the way back from Yellowstone on rt90. We took the entire month of May and put on 9000 miles. Climate is very different when you get up in elevation. Very beautiful trip,but be prepared for some weather extremes.
We drove straight to NM before we really began touring. Grand Canyon is always crowded but is awesome. Zion was jam packed. We couldn't find parking within a mile of the visitors center. The scenery is truly breath-taking,but the ride was like Disney Land. Canyonlands,Canyon D'Chelley (fabulous),Capital Reef,Arches,Natural Bridges,Mesa Verde,Kodachrome,Black Canyon(spectacular),etc. All well worth visiting.
I'm near you (Tatnuck Square area) and will be very willing to go over our trips with you. We have loads of brochures that would definitely help you plan.
