OK, take your pick: 1) Arizona or 2) Utah. Both are epic. ARIZONA: Palm Springs to Prescott then over Mingus Mountain through Jerome (Arizona) to Sedona There are quite a few gorgeous campgrounds in Oak Creek Canyon, but I'm not sure what the policy is on dogs. And they fill up quickly in summer. Anyway, this would be a great place to camp for a few days and explore, so many great hiking trails and things to see and do. From Sedona, head up the canyon to Flagstaff then to the Grand Canyon South Rim (unless you've already been – but I've been 8 times, and it never gets old for me). There are campsite just outside the park entrance. From here you could take a side trip to Page and see Horseshoe Bend and Antelope Canyon (book your tour in advance or you may not get to see it – also, dogs are not allowed). Head to Kayenta then through iconic Monument Valley Next is Mesa Verde National Park in southwest Colorado. From there, pick your route through the Rockies to Fort Collins It'll be a bit slow going but the scenery is GORGEOUS and there are trails and camping along the way. UTAH: Palm Springs Las Vegas with a possible stop at Valley of Fire State Park Then north to St. George – I definitely recommend Zion National Park but it may be tricky with dogs. You can't drive through the park anymore, you must use shuttle buses and I doubt dogs are allowed on those. But there are many other great parks in the area including Kolob Canyons (part of Zion), Cedar Breaks National Monument, Bryce Canyon National Park and Capitol Reef National Park From there head east to Arches National Park outside of Moab. Then you can take I-70 to Ft. Collins, stopping along the way as you like.