I paid Evans Tire (regional San Diego chain) for a lifetime alignment, and got 3 or 4 uses out of it before the SOBs told me they had a policy that if I replaced any part of the suspension, then I couldn't just bring it in for a free alignment anymore. If I had put in a new part, like tie rod end, ball joint, LCA, that I had to PAY FULL PRICE for a single alignment to "reactivate" the lifetime alignment service. BS! I'm always breaking tie rod ends or replacing LCA bushings or something.
Evans Tires is now on my ever-growing boycott list of cheaters.
I've also heard very bad stories about many national chain stores, such as Firestone. Discount Tire, Costco, and Walmart refuse to work on vehicles with wheel spacers, so they're off the list as well.
For the best place to locate reviews of local shops, I recommend
www.yelp.com. You'll get a lot wider range of local reviews of owners with different vehicles. Different than this sort of forum.
Just ask the shop before you leave it - do you know how to adjust camber and caster on a trailblazer? If they claim (as some shops have been known to do) that we don't HAVE a camber and caster adjustment, flee. We're not some lame MacPherson strut Honda.