I have a good friend in LA who loves scenery and hiking. Last year it finally worked out for us to meet there and drive to Utah for his first visit there. We were only able to allocate 5 nights to our trip in the last week of October. Joel's in his 60's but is in great condition (runs for an hour most mornings and bikes most places because of miserable traffic and parking). My hiking days are pretty much over, but Zion's my favorite place in the world, and I am content with easy hikes and lots of wonderful scenery. Over the years I've hiked in all the NP's and most of the SP's in Utah.
We left LA early on Day 1, stayed in Hurricane for cheap, easy access to Zion. On Day 2 we spent a few hours in Zion, then drove back to I-15 to Kolob Canyons for more stunning scenery and a short hike. Then we drove to Moab for 2 nights. A good bit of the drive was in darkness, but it was all interstate. We did lose our internet connection (GPS and World Series scores :-) quite a bit. We stayed on the main road, convenient but not much else. Be sure to make entry reservations for Arches every day. Ours was for 8-9 am. We arrived a few minutes before 9 and there was already a longish line of cars waiting for the next entry time. Since it was the end of the season, we had no trouble finding parking all of our stops and the toilets, though spartan, were clean. We spent one entire day there and Joel was able to do the main hike - it took him about an hour longer than planned because he got lost more than once. He wanted to do the sunset hike to Delicate Arch but was dissuaded because of the likelihood of some rain (it had rained off and on during the day) especially on the slickrock and he didn't bring hiking shoes. Unlike the other NP's in Utah, you'll spend virtually all your time miles from the Visitor's Center, so get all your information (and maps!) first thing. And be sure to have plenty of food and water with you. 4 nights in Moab sounds like a lot to me unless you are planning to spend a day in Canyonlands.
On Day 4, we left Moab early and drove to Capital Reef for a brief visit (a lot of the roads in the park were closed) and continued on to Bryce for 2 nights, giving us one full (freezing but dry) day in the park. We did the scenic overlook drive and Joel did some hiking along the rim. After lunch at the Lodge (lovely setting, good buffet) Joel did a hike down through the hoodoos. We stayed for sunset to end our single day. I would recommend your spending 2 full days in Bryce. Joel's impression of Bryce "The Grand Canyon is just a hole in the ground in comparison." On Day 5 we left early to drive into Zion from the east - one of the most scenic ways to see Zion with the sun at our back. Joel did a short hike (1 hr) and then we stopped in Springfield for lunch before heading home.
Are you driving from home? Your itinerary suggests a one-way route, but I figure you'll do a loop. Where you can, it's worth it to take the slower, scenic roads. You don't lose that much time (except for stops for photos).