I'm in the D.C. area, too, and I've put a lot of miles on my car getting equine experience. My current job is a 50 mile drive. However, actually getting my foot in the door was not too difficult, since I had a lot of previous horse experience, and, as david said, once you get started, one opportunity leads to another.
Research experience was also easy to get, although I may have been unusually lucky. I just asked one of my professors if I could volunteer in his lab, and I hadn't been there a month when he started planning a project for me to take on as my own.
If anything, getting small animal experience has been hard for me because I am limited by the amount of time left over after commuting to my equine job, school, and my research lab -- I can't make a significant time commitment to a SA vet at this point. I've done some shadowing with a horse friend who's a SA vet, which is probably how I'll get all of my SA hours, but I drive 20 miles to get to that, too! My car is my second home.
I haven't even thought about getting food animal experience because I'm swamped with the rest of it, but I'm sure that would be quite a hike, too.