Just joined, first post, couple week old thread, I'll try to make it worth it.........
Currently have a 1998 Grand Cherokee. The 4.0 GC is reliable, gets decent MPG's (19-20 backroads, 18 interstate, both with 2" lift and 31's) and is down right easy/cheap to fit 31's on. Rear axle is the weak point but fine if you keep it open and stick to 31's. On paper it's only slightly larger than the Cherokee in the real world it's much better on anyone riding and more storage. The Cherokee is gone the GC isn't. It's also a better vehicle than the ZR2 pickup I used to have. Not the electronics mind you. Chrysler electronics have always been notoriously fussy but over all it's just better.
Don't go throwing the idea of full size out either. One of the reasons I ditched the ZR2 was the MPG's wasn't much if any better than a full size Ford or Chevy. Extended cab Fords with 4.9's and 5.0's can pull 16, maybe 17-18 if you stick to back roads. Their Chevy counterparts will do about the same, maybe slightly better for I've always found a 350 SB to be better on gas then their Ford counterparts. As for young family's and extended cab trucks........ we hauled 2 daughters all over the western U.S. riding in booster seats back there. No complaints, plenty of room, access is tolerable, great times were had. Look close at the Broncos.