If you live in the Steele Creek area, Tuffy on S Tryon is a pretty good bet for auto service. Oil changes, state inspections, full diagnosis, they do it all. I've sent probably half a dozen friends here and haven't heard a bad thing yet. They always seem to have better prices than the local competition, yet I haven't noticed any major problems with their workmanship. I've only had to have a re-work done once... when they mounted a tire inside out (these were asymmetrical tires). Not a huge problem (I didn't even notice for a week) and they were very accommodating when I brought it back in, putting me first in line and not charging me a thing.
Unlike a lot of places, the mechanics here don't try to sell you on a bunch of crap you don't need. They diagnose the issue efficiently and any recommendations they have are probably worth listening to, at least in my experience.
The waiting area is relatively clean (about what I'd expect for a service center) and offers a TV, comfy chairs, and coffee/water and drink/snack machines.