www.ecodetuning.com is very owner/tuner friendly. They know just about everything you'll need for Audi/VW tuning and can give great advice. www.ingolstadtwest.com is high-end full service shop with a lot of experience. Both sell APR parts (so will show up on APR's dealer list) as well as other brands.
They pointed me towards a very customer focused shop here in Northern California. What's cool about the place is that when you start talking mods- the guys in the shop get excited when pulling parts that the customer is thinking of installing.