I've used alamo three time this week, booked them each direct, LA, then Mexico and back in LA now. They include collision damage waiver fee if you note you're an Australian.
just remember, they are all about the up sell and the sticker price you see is never the price you pay because they exclude taxes from it.
the other thing to note is no matter how much insurance you take out there are 'out' clauses all over the place.
As a side, re the Mexico hire. You know how when you hire a car they have a little car drawing and you mark all the existing damage in the before driving out. Well after the rental agent and myself did the walk around every panel had damage. They were. Also very careful to check the spare tyre when I returned to make sure I hadn't swapped it out with a dud.
matt