Tiffany, I think I recall you posting you were going to use MTH RealTrack on this layout. Having built a number of door layouts over the years, you might want to consider using a indoor/outdoor low pile type of carpeting. It's simple, durable and will help with some noise reduction. And it'll help keep track in place with a minimum of screws.
Depending on your own preference, you could use green, or I'd go for a neutral gray or brown color. You could add scenic plots later with green colored felt. Ace's suggestion isn't a bad one either, though I think indoor / outdoor carpet would sit flatter. His point about moving scenery things around on a small layout is a good one.
You might also want to consider (depending on how you elevate your door layout: milk crates, sawhorses...) adding a strip of bracing to the door to help prevent sagging of the door over time. The bracing inside the door was never intended to take the weight of trains on them. I add a 1x4 strip to each side of the long length of the door for added strength, which also gives some convenient space for control buttons.
I always use 027 track on door layouts with self adhesive foam beneath the metal track ties, and then added brown ties cut out of foam from like Hobby Lobby... really makes for a quiet layout. I'll paint the door surface a neutral brown or grey for the ballast, place all the track down and then over time add the "scenery" with different earth/vegetation type colors of acrylic paint.
Door layouts are fun. They're a bit of a challenge, but it's neat to see all the various approaches folks have taken with them. One of my early door layouts was multi-leveled with a high-rail scenery approach. That was fun to make, but with a small layout - as Ace said - keeping the scenery simple so you get variety by moving around, helps to compensate for the small space.