For anyone in the DMV (DC, MD, VA) area:
Wheaton Service Center
11321 Fern Street, Wheaton, MD 20902
(301) 949-3144
https://www.wheatonservicecenter.com
Tom (owner) is a stand-up guy, came from VW dealers back in the 90s, absolutely encyclopedic knowledge. They exclusive service VWs, been in MoCo since the early 60s.
I've had all my non-warranty work done here; as
@MonkeyMD said, it's the little things. For example, they caught a differential seal leak at my first oil change (awesome attention to detail, for starters) and then rather than try and charge to fix it, he not only recommended VW look at it instead, he also set me up with a contact at a local dealer who got it all straightened out under warranty without me having to do a whole song and dance. I was sold after that.
Very fair pricing too; just had my 20k service done there, plus 3 yr. brake fluid and differential service. NGP quoted me $618, Tom did it all for $402 AND was able to get me in and out same-day, where NGP was quoting me about a month wait for an appointment. Two thumbs up.