I think its worth it if you have older cars and take long trips (or commute far).
This past year was the first year in the last 3 or 4 we didn't really use it, but we had several years where we used all of our 4 tows and we still own the car that was towed. DH also drives 25 miles to work, so we have the plus because we just can't deal with the hassle of having him break down near work and then either paying for a tow back to home or having to get it fixed at some random place there to avoid that.
We also drive long trips (days of driving, etc.), so I like having the security knowing we don't have to worry about that.
When I had my road trip van, I had them tow me many times, once 75+ miles from yellowstone to Jackson Hole. That would have been very costly - we were pricing just a cab to get the other passengers down and that would have been nearly $200! (luckily we worked it out with the tow truck driver, he let us ride in the van as it was strapped to the flatbed, not towed).
I also have taken advantage of some pretty cool discounts. When christmas shopping at an outlet mall, I got 40% off at the reebok outlet for being a AAA member, and most of the things were already 40-50% off because they were having a big sale. You can also usually get a $5-10 hotel discount if you ask.