I HATED the 3.07 gears when I upgraded to 30" tires. But then I demand more from my truck than being mere transportation. If it's not fun to drive, why bother? :D
I don't think you can get 3" from adding Explorer leafs. Maybe an inch or so. AALs are pretty cheap, but make sure you get one for an MJ, as the XJ ones will only lift your truck half as much as they would an XJ.
Also, from what I can tell, 3.73 gears were more common in Grand Cherokees than Cherokees so keep an eye out for them too.