On a good-weather day, Hell's is hard to beat for scenery. LaSal mountains on one side, overlook to the Colorado at the far spot of the trail, views of Arches NP, and the sandstone 'roller coaster'...but I'm sure you know all about the geology there

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Hell's is not very difficult, it's more of a case of NOT getting nervous. Traction is great, and as long as you stay out of the optional obstacles, you'll do fine - just stay on the trail markers. As for family-friendly: I'm not quite sure what that means - Hannah did great on the Unsurvivable Obstacle on the C-Gap run... Fins is Hell's-Lite, sort-of, same mountain panorama, but not the river. Both trails are close to town. Fins has the advantage that you can cut out and get back to the main road easily if need be; can't do that on Hell's. Porcupine is driving along the cliff, can't let the kids out ot the truck and let them out of eyesight. Hell's isn't that bad in that regard; neither is Fins.
I'd make sure your wife would rent a Jeep in Moab, so she can drive herself on the runs, just in case she doesn't trust you...;p That aside, a very enjoyable drive - entirely on blacktop is the ride up Hwy 313 to Canyonlands NP, out to the main overlook, or the drive in Arches NP.
I'm noy trying to talk you into any particular trail - heck, my first trail in Moab was Gemini Bridges... but Hell's Revenge is - in my opinion - a must-see-must-do, and that's why we took Kevin and Rob there last year.