It'd be nice to know two things in order to help:
1) How your rig is currently equipped.
2) What kind of trails (difficulty rating) do you intend to run.
The obvious have already been pointed out as far as equipment: Sliders, skids, front and rear tow hooks, strap, etc. Lockers depend on the trail but most intermediate to moderate trails can be done out there with out them - but a rear locker is beneficial.
Keep in mind that unless you trailer your rig out there, you're gonna give your XJ a pretty good work out just getting over Vail pass on the way. The daily flatlander use may not have presented any concerns recently, but after the pass run, it may develop other issues - hense the other poster's concern about the cooling system.
Once in Moab, keeping both you and your rig cool in 120 degree heat is pretty important. You may not have heat issues here in Colorado, but Utah is a whole different animal - the average daily high temp in July is 98 degrees. You gotta remember that many trails out there are sand/rock and reflect the heat back up from the ground - and the canyon walls do the same - you'll feel like you're driving thru a brick oven in July - the reflected heat is always hotter than the ambient temperature. Definitely check the condition of your radiator by draining a bit of coolant so you can inspect the top few rows of the core - look for calcium build up to see if there's a possibility your radiator might be restricted. Be sure you have a way to override the aux. fan to run manually as a cooling back up plan. Seriously consider installing some hood vents - they do help. If you question the condition of your water pump, save yourself the headache and swap it out before - or at least pack one to go with. Pack coolant, the pre-mixed kind. Between you and the other rigs, each should carry a gallon to share with anyone that might need it.
Always bring lots of water - more than you think you'll need. I was shocked at how much water I drank the one time I went out there in mid July (never again). Hats/ball cap/towel to put over your head if you end up having to be out of the shade for any length of time.
As far as equipment, I'd make sure someone in the group has a puncture repair kit. Moab likes to eat stock steering parts, so spares for that are always a good idea as are spare front shafts, and u-joints for the drive shafts. A spare set of radiator hoses and a serp. belt are a good idea too. Check the fluid levels in all locations and particularly in the transmission and t-case.
Have a blast and stay cool! :thumbup:
