Hi Deborah -
I'm very late to the party but somehow missed your post until it was resurrected by the Badgergrrrl's entry above. We have hiked all three of the parks you've listed more than once, and all three offer the sort of shorter hikes you're looking for. The most recent trip had us in the Moab area two years ago in late April - so roughly when you plan to visit - and we were surprised to find Canyonlands Island in the Sky unit - the closest of that park's units to Moab - busier than on previous trips. We skipped Arches as we'd already done that one 3 times prior and we knew it would be very busy. No reason for a first-time to stay home, though!
A couple of questions? With 10 - 14 days you have time to add stops at more parks, both National and State, plus so some local hikes such as the previously mentioned Canyonlands NP Island in the Sky, Dead Horse State Park (very near IITS), Coral Pink Sand Dunes (enroute from Zion to Bryce), Goblin Valley State Park (between Capitol Reef and Moab), etc. As you'll be driving between Zion and Moab, Capitol Reef NP and Goblin Valley State Park are along the way so for sure spend some time either or both.. As this post is almost 3 months past your original query, have you made your reservations yet (I sure hope so!!!) and can share those so suggestions can best apply to where you'll be and for how long?
As well, there are 3-5 mile hikes that are flat and easy, and 3-5 mile hikes that involve some scrambling/climbs up/down but are not at all technical. Can you be more specific about what you feel you can do? I'd love to give you great suggestions for some within your abilities. BTW, the DH and I are both 70.
In addition, your BEST sources of info are the park websites themselves. All of them break down their hikes from easy-to-difficult, and the State Park websites and the town of Moab site have useful info too. An example for Arches hiking (we have done all on the list + Fiery Furnace):
https://www.nps.gov/arch/planyourvisit/hiking.htm
DO look at both Canyonlands Island in the Sky and Capitol Reef:
https://www.nps.gov/cany/planyourvisit/islandinthesky.htm
https://www.nps.gov/care/index.htm
The Horseshoe Canyon unit of Canyonlands is great but involves a loooong gravel road that isn't passable when very wet, and a 7 mile RT trek including a pretty good climb out. The Needles Unit also offers terrific hiking is also great but isn't exactly along your route, and may also be more than you'd like to take on.
Goblin Valley can be a stop-by for as little or longer a time as you wish:
https://stateparks.utah.gov/parks/goblin-valley/
Dead Horse Point:
https://stateparks.utah.gov/parks/dead-horse/
Moab:
https://www.discovermoab.com
One of America's top-rated scenic drives is between Bryce and Capitol Reef:
https://www.visitutah.com/articles/the-all-american-road-scenic-byway-12
We have stayed in Torrey and hiked Lower Calf Creek Falls, parts of Capitol Reef and Kodachrome State Park, mentioned in the articles.
It would be most efficient if you could fly into one airport and out of another but you'd need to explore drop-off cost/ability. Specific to Arches, plan to get up and to the park EARLY - if not camping in it - to avoid long backup lines and temporary entrance closures due to crowding. This park has previously required advance entry reservations during peak season (April - October) but it's unclear if they'll continue that this year. If they do, you can get around it by entering before 7:00 AM...which I'd STRONGLY advise in any case.
Julie, give a private message shout if there's anything I might be able to offer up for you too? :O)