Add me to the Alamo fan club. We used them for our January trip and it was the easiest thing ever. Our rates were phenomenal ($80 for the week!) and I loved that we could pick our own car. I was prepared to be asked to add on insurance or some additional costs at the counter, but the only they asked was if we wanted to prepay for our gas. We booked a full size car and ended up with a really nice Nissan Altima. Within minutes we were done at the counter, had selected our car, and were on our way. I wasn't prepared for how simple it would be! I signed up for their insiders club and got a $40 off coupon and got the membership discount as well. It blew everyone else's rates out of the water!!
My suggestion would be to sign up for a few different memberships (I chose Alamo, Enterprise and Payless) and see what kind of offers you get emailed to you.