I'm not sure all of what quest diagnostics offers (I think basic tests, glucose, etc), but they definitely do drug screenings for larger companies as my new employer sent me here one afternoon. They're tucked away on the first floor next to a pharmacy in a odd medical park, and the waiting room is fairly small.
They were very efficient with their set procedures (a lot of "now stand here", "now wash your hands") and nice, but with an almost intimidating side to let you know they mean business, and don't you dare try to pull anything. I was in and out in under twenty minutes, so definitely no complaints here (it just seems weird to be a "fan" of a lab). They also close for an hour around lunch time.