barbokw,
a couple of summers ago my wife and i flew into LAX and traveled a good portion of the southern end of the state. we, too, thought that since we were in california we would rent a convertible. we did, and it has been one of the most memorbale traveling experiences ever. it meant extra money, but i would not trade that time driving around with the top down (even when it was cold in the higher elevations and in san francisco - and the heat on) for the hundred or more dollars it cost. so, my advice would be.... rent yourself a convertible and enjoy the ride! we rented from alamo, but it was at about the same price as you are saying enterprize is quoting. the problem for us now is that every trip back to california will be plagued with the convertible "need." we are heading out again this sunday, taking our 17 year old daughter to see the state. with the extra expense of another person we will have to pass on the convertible. i keep watching the discount travel and car rental websites for last minute deals, but i don't think it's gonna happen. have fun.