Definitely avoid the scooters! Too dangerous on those sandy roads.
We rented a moke for the first time a few months ago and while it was fun for about 20 minutes it got old very quick. You have to go so slow because the roads are so filled with ruts and holes so you spend too much time driving. I don't mind a bumpy ride but this borders on painful after a while. They are all stick shift too so if you don't know how to drive manual, definitely don't consider it.
Overall, for the day we called it a "goof" but for actual transportation on a 2 day stay, get a real car.
Yes, do the Horseshoe reef tour with either Sherwin or Kelly!
Wonderful breakfast at Pink Flamingo and the owners are great.