Double Arch (Arches NP)
Isle in the Sky (Canyonlands NP) seen from Dead Horse State Park
Housing and food options:
Moab is full of hotels/motels. Sleep Inn & Suites Moab was my satisfactory choice. Restaurant recommendations: Dewey's Restaurant and Bar (delicious steak, uncertain about vegeterian options), Thai Bella Moab, Moab Canyon Pizza Co. and Sultan Mediterranean Grill. Salads and sandwiches to go (for hikes) at City Market.
The unmissables:
1. Arches National Park:
Delicate Arch : hike of about 1h/1h30 one-way, very tough in the summer because of the heat, pretty easy otherwise. Sunset is the best time to do it. Legendary arch that is the symbol of the park and of the state (it's on all the licence plates!)
The Windows et (especially) Double Arch: very short walk to admire these spectacular arches.
Devil's Garden: area with lots of incredible arches, there are many different hike options, between 1h30 and 3h depending on how much time you have.
2. Canyonlands National Park:
The different overlooks from the area of the park called Isle in the Sky : allow for up to 3 hours to see all major lookouts. The most iconic spots: Mesa Arch (recommanded at sunrise, overrun with tourists during the day), Green River Overlook, Grand View Point overlook (don't stop at the parking lot, walk until the end of the path, about 20 min one way)
3. In the area, outside the two national parks:
Corona Arch: a nice hike that starts on the Colorado bank near Moab, about 1h/1h30 one-way, especially nice when the weather is nice. Early morning is the best time for the hike. Keep going until the end after you reach the arch, there's a beautiful spot for a picture and/or a picnic looking back at the arch.
Other points of interest:
1. Canyonlands National Park:
Still in the Isle in the Sky area: Upheaval Dome, surprising geological formation. Continue until the second overlook (not far, about 30 minutes one-way), cool panorama.
In The Needles area (other part of the park, about 90 min south of Moab by car): Druid Arch (about 2h/3h of walking one-way), mostly easy hike except for a few steep spots near the arch, but nothing too bad with some good hiking boots). Beautiful landscapes along the way and the arch is majestic. The Needles area is much more confidential and there's way less tourists, the road leading to the trailhead (Elephant Hill trailhead advised, other options available) is unpaved towards the end, check road conditions on the park website before going. Other hikes in the area I didn't have time to do but that seem interesting: hike to Confluence Point to see the confluence between Colorado and Green Rivers; the Devil's Canyon area with beautiful landscapes.
2. Near Moab:
Dead Horse Point State Park: easily combined with the Isle in the Sky area in Canyonlands National Park. Extraordinary viewpoint over the Colorado and Isle in the Sky, especially when the weather is nice. Quick to visit, possibility of doing a short walk in the park.
SR 128 heading east from Moab along the Colorado river. Incredible landscapes along the road. Point of interest worth a hike: Fisher Towers, very spectacular rock formations, very nice hike up to the Titan.
Longbow Arch: start from Longbow Arch trailhead on the Colorado bank near Moab. Easy and quick hike (about 1h30 round-trip). Petroglyphs and dinosaur footprint fossils near the trailhead are worth the 5 minute detour. Easily combined with a trip to Corona Arch.
Mesa Arch (Canyonlands NP)
Corona Arch (near Moab, outside the two national parks)
Delicate Arch at sunset (Arches NP)
Druid Arch (Canyonlands NP, in the Needles area)