Moab is not just an off-roading trip, it's a vacation with lots of places worth visiting! As John said the scenery is just amazing, it's the beginning of the Grand Canyon and we've heard people say it's more amazing that the GC.
You can also rent Jeeps there in case you don't want to drive your truck all the way there. They limit what trails you can go on, but there are so many you won't run out of places to go.
Back in '04 the trail guide book to have was Guide to Moab, UT Backroads & 4-Wheel Drive Trails by Charles A. Wells. You can also find GPS tracks online. Either one is needed if you don't have experienced guides as it's easy to get lost in the desert. I don't know if it's been revised or there's another recommended book, but do your homework and get organized before going down.
There's a Calgary club that goes down every few years, John might remember the name, they're a great group of people and know the area well.
Anyways, if you get serious John and I can give you more advice.
