Renting a Jeep is definitely a good idea. I didn't but wish I had.
It's so fun to explore Aruba and believe me you don't want the fact that you rented the wrong vehicle stopping you from going where you want go. And don't let the road conditions around the hotels, restaurants and shopping areas fool you. The back roads, like in the national park get really rough. You may also see some shortcuts that you want to take, like one we saw to Baby Beach, and not be able to take it because you rented a car. Or like us, you might get halfway across the shortcut, be really worried your tires are going to pop because it's so rough, turn around, go back and take the long way
. Not a good feeling
I hope you get a Jeep and be happy.