If you do decide to get a car .. be careful how you book it. Most Americans seem to get Insurance cover on rentals from their credit card companies or household Insurance.... so they can get these $25 PL deals....
That does NOT happen with an Aussie CC (or household Insurance policy).. and I suspect not with a Brit one either... Most (all?) Travel Insurance covers the EXCESS only.. don't even think it covers the whole thing..
Long story short.. If your CC/home insurance provides no coverage you WILL need the "CDW or LDW" (Collision Damage Waiver/Loss Damage Waiver)..
It is not Insurance as such.. it is a fee paid to have the rental company "waive" their right to hold you responsible for ALL costs associated with damage to the vehicle...and it CAN be $$$$.. (Like $19 a day extra!)
..but doesn't have to be.
Sites like
www.cheap-car-rental.com offer rates to foreigners that are all inclusive.. and generally pretty decent. The Alamo site also does so if you make sure to enter your country of origin....
Just be careful........