I've never wrapped a butt. If yours is a bone in butt, don't sweat the temps, beyond using them as a rough idea. Whenever the bone can be pulled out of the meat, clean, she's ready for a rest and pull.
I've never spritzed a butt, either, and never had a dried out one. Not to be overly harsh, but spritzing a butt seams to me like a solution to a non existent problem. Every time you open your smoker to spritz, your losing heat and extending your cook time. I figure on butts taking 2 hours per pound. That's pretty much the longest I've had them take, (smoking at 225* to 250*), sometimes they take a little lless time but I plan for 2 hours per LB.