I can't remember exactly how much it costs to join AAA. I have 3 members of our family on our membership. You could call or log on to their web site and find out. As far as the differences between AAA and DC discounts, they are comparable to each other. You can only use one or the other, not both. I have both memberships but decided to use the AAA discount for our Jan. 2003 trip because I liked the AAA payment policy better. AAA requires one night's deposit and balance at check in. DC requires $100 deposit and payment in full 21 days before check in. As far as memberships go for each, they have more than paid for themselves in my case. DS had to use AAA to be towed just this past weekend (away at college), and we have gotten other lodging discounts elsewhere. I also purchased discount Universal tickets through my AAASouth office. We have used DC for discounts on rooms, passes, meals, and Downtown Disney shopping. Just my experience!