I would most likely stay with a matching color theme in my car (boston green exterier with dove gray interier), but honestly...it should be your own personal preference and no one else's. That being said, I'll give some more of my thought..
Having the same color exterier as yours...I can imagine the car with black interier and I think it would look really good! But if you have any photos of your car that capture the interier trima s well...I can photoshop it for you to change the headliner to black so you can get a quick taste of what it will look like.
Replacing the headliner with the same color might not seem too exciting, but really...it's would make the over all appearance of the car from the inside seem much newer/well taken car of. The black headliner would stand out and might make a great contrast...but sometimes it is the details that go somewhat un-noticed that create the nicest/most eligant appearance.

But like I said before it all still depends on your likings.
@Steve...John is right...videos would be excellent! You can upload them to youtube and post links here if you want!
I recently bought a new guitar so my car is yet again pushed off the top fo my list of things to buy for, haha. It works out fine tho, cause I play guitar a heck of alot more than driving while I'm here at college. The guitar can pick up babes just as easily as the car, haha.
Here's a picture..
