Personally I'd cut out visiting d/t SLC. You'll need to lot more time to explore Bryce and Zion (the main visitor area of the latter can only be accessed by bus for those not residing at the park's lodges). Capitol Reef seems to be worth exploring only if you have time, plan to camp, and go on the dirt roads (need a 4x4). It's worth spending a day each hiking through the hoodoos at Bryce and at least up Angels Landing at Zion. Maybe cut out Arches and Capitol Reef this trip, and fit Cedar Breaks inbetween Bryce and Zion.