One piece of advice i would offer, make sure you hire your car from Autoriesen or Cicar, both these companies offer full damage waver included in the price, they do not attempt to scam you for a scratch when you take the car back, there are plenty of horror stories about Gold car and others doing this, we have seen the arguments at the airport, people forced into paying for extra insurance etc, we hire a lot, so we have our own yearly collision damage cover, it costs £40 for the year, no probs if you use the companies i mentioned, but we also hire in Greece a lot, the two companies do not have offices there. the driving in Tenerife is ok, but a lot busier now, watch out for hidden speed cameras!