The car rental agencies in Aruba are located immediately across from the entrance to the airport, just cross the small street where people are getting picked up and dropped off, and you're there.

Be aware that the offices close at 10pm, or earlier. American Airlines from Miami is currently coming in at 8:30pm, but if you're flight is delayed like mine was, you might get to the offices right at 10pm, like I did, to find your agency closed.

My reservation was with Avis, and it actually was the only office closed at the time, although other offices were closing very soon. For this reason, I do not recommend Avis. The closure cost me an additional $40, a couple hours of my time, and the related hassle.

Based on staff and availability on the night I was there, I think the best place to rent if you're landing in the evening might be Hertz if you can find a reservation at a decent price. If you arrive during the day, it probably doesn't matter.

If you do not or cannot get a rental after you land in the evening, you'll have to take a taxi to your hotel. If you call the office the next day, they will come to pick you up, that's what I was told. Apparently this is not too uncommon an occurrence.

My weekly rental for an economy vehicle in September/October 2012 came to $22US a day before taxi to give you an idea of the lowest price.

You might be able to get by with taxis and buses, but based on the availability of each and what I think would be excessive costs for taxis, I would recommend against it, the car rental is not that expensive.