When visiting Rio de Janeiro I would suggest pre-booking you airport to hotel taxi transfer.
We've visited Rio de Janeiro twice. The first time, our first to Brazil, we arrived at the airport and were accosted by many people wanting to carry our bags, or offering us rides in their 'taxi' - essentially just family sedans with their brother or father driving! We had read on many forums that it was fine to turn up and get a taxi upon arriving. Perhaps it's ok to do this in off peak season, but it certainly didn't work for us in January!
The last time we went we did a little more reasearch and found a company online called Rio Airport Transfer (www.rioairporttransfer.com), they're a UK registered company so we felt a little more comfortable about booking through them.
We booked a trip with them and one of their drivers meet us on the main concourse at the airport and delivered us safely to the hotel in air-conditioned comfort.
The service is around £10 more than getting a taxi at the airport, but knowing someone was waiting for us made me feel a lot more secure. Highly recommended for those who prefer a little less stress and haggling.
Pete
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