I bought the Firestone Lifetime Alignment for a number of my cars. My 1981 Mercedes has certainly gotten value out of the purchase over the last 24 years, and 500,000+ miles. My 1996 Subaru has gotten good value over the 9 years and 275,000+ miles I owned it.
Firestone re-aligned my vehicles every time I asked, at any store across the US I took it. My only issue with Firestone is the time it takes to get the car into the service bay.