We go to Moab at least twice a year and love it. We have done a broad range of trail difficulties from dirt roads (Onion Creek, etc.) to difficult, (Pritchet Canyon, Rusty Nail, Moab Rim, Hell's Revenge, Metal Masher, Steel Bender, Cliff Hanger, Golden Spike, Poison Spider, Gold Bar Rim, etc, etc.) All of them offer excellent beauty and sure to please fun.
Be prepared to/with:
1. Come back because that desert calls to you when you're not there. You will be hooked
2. Pleanty of water, tools, fuel, spare parts. It is not a place you want to get stranded unprepared.
3. Bring multiple vehicles with you. Don't go out alone, and be sure somebody knows what trails you're running and when so that if you don't make it back, they know where to look.
4. HAVE FUN!!