In reply to sean1:
Just avoid goldcar like the plague on steroids. (google if you want the horror stories). I think they are just based around the med though.
Car hire firms generally are becoming more of a pain in the arse - they are having to reduce their headline prices to compete over the internet on comparison sites etc and are then ramping up the add ons.
That said, if you stick to a mainstream firm you are likely to go less wrong than someone more obtuse.
(I have had many a happy car despite my post, I am not a complete grouch)