Update: 4wheeling in Kauai
Kauai has some great trails. Not to technical, but fun. I rented my Jeep from Budget and the rental agent says, "We don't look for dings and scratches only major body damage. Everyone uses them (Jeeps) around here." Waimea Canyon has some pretty cool stuff on the East side. We found a cool beach that you had to 4wheel to also. Definitely worth getting a Jeep. We found a really cool trail that was to rough and muddy for a stock Jeep. I wish I had my truck for that one!