I used to live in Fairfax, VA. I never trusted Fairfax Honda -- I have heard too many horror stories (for example, they claimed to have changed out my friend's transmission fluid, but it was clearly not clean fluid in there when he checked it!). I'd buy parts from their parts department before I discovered the joy of online shopping...
Moore Automotive in Fairfax was the place I'd go with my Accord... I don't know if they have everything they'd need in order for them to work on an Insight (e.g. computer equipment). They can do basic stuff to it, of course. If you go there and there's this huge surly guy named "Dave" behind the counter, tell him Cleopatra says hi. He'll get a kick out of that.
I went to Bill Page Honda in Falls Church once. They tried to convince me that I needed 30K service. I told them they were full of it, that the car didn't have 30K miles on it... they said, it does, we checked! I said, look doofuses, you accidentally switched the display to KM... and sure enough, they had...
Good luck!
-fly