I would appreciate some suggestions on renting a car in Spain for 2 weeks in August. Best company to use, what to watch for, etc.

Try Carjet.com
I've rented from them the last 2 trips to Spain and got the best price, no real problems.
You rent the car with a full tank (cost for the tank is the only extra price, EVERYTHING else is included, extra drivers, etc.! ) and return with empty tank so no last minute frantic searches for a gas station on the way to the airport.
Have a good time.

We used Hertz as it was my corporate partner; DH uses Sixt. We needed a one way rental without an enormous drop off charge which is negotiated with my employer.

Auto Europe is a consolidator that finds you the best price among several different companies. If you find a beter price by contacting a company directly, Auto Europe promises to either match it or beat it. Book now from home to get the best deal: www.autoeurope.com.

We used Hertz for all spain trips. Like it because there wzs no drop-off charge (were taking Spanish cars back to Spain) and when we had a (we thought) problem with one car they sent a mechanic to the hotel to look at it - rather than our having to trek all the way out to the airport and back. (It turned out it was only a fuse - but when we saw the light flashing was "frenos" we got a little nervous.)

Rented from Avis two years ago -- was just hubby and me on the Costa Brava and they had a great deal on the cutest little Peugeot convertible. I felt like a Bond girl. Or whatever the Peugeot 206cc version of a Bond girl is .

Last year we found the best deals at Nova (http://www.novacarhire.com/) for southern Spain, but as it turned out we took trains instead. Good Fodorite reviews of Nova on this forum. You might do a search.

I just returned from 19 days in Spain and rented a Ford Wagon with automatic and a/c from http://www.carjet.com/ with excellant results. The rate was very good(232 euros/week) with a discount for booking it online. I took it with full insurance. I did not want any hassle with my credit card company if I had a claim. As previously noted you pay for a full tank of gas(71 euros) and try to return it as empty as possible.

I too have been pleased with AutoEuorope, paying in advance for great savings and excellent service. The payment is refunded if plans change.

IŽm spanish. You have several options.
Most famous rent-a-car companies are Avis and Hertz. if you are interested in cheaper prices then try pepe car or easy car. YouŽll have no problems with any of them.