I did the quad racers (4 wheel atv's) with rancho notorious 2 years ago, it ranks as one of my favorite shore excursions. www.ranchonotorious.com
is their website.
The last time in aruba, I took a "jeep safari" that went to some lesser known places in aruba, like a natural swimming pool in the ocean, surrounded by giant rock formations. ( www.abc-aruba.com
) we took the half day, NOT the full day. The full day does not go to the swimming hole. (click on "xtreme safari") this is more of an eco-tour.....VERY rough "roads"
Hope this helps.