We have the principal and vice principal on the executive board, though they really don't seem to do much. We have 1 teacher rep. She reports back to the other teachers what happened in our PTA meeting, and personally runs 1 after school program per grade(each program lasts one or two days). Other than that, our teachers do very little--field trips are almost non- existent. My group (not the PTA--we're a nonprofit raising money for a playground currently) has spoken to our principal about this, as one of our goals after the playground is to have a running budget to do things like fund field trips.
If your principal sees the need, it's really up to him/her to get the ball rolling, including involving himself in activities and programs. People will follow where led. Keep communicating with your principal--I don't know if your situation is like ours, but it was uncomforatble for us to say, "the teachers seem to have little interest in being involved outside their clasrrooms," but we did get that out, and the principal said she will look at it.
Bertha is right, she is lucky that her teachers are incredibly supportive, but she sells herself short. I know her, and see what a tremendous job she does, and she's instrumental in the success of her school. My philosophy for getting teachers involved in my school right now is to just keeping the group and our projects and activities out there in the public eye, and we're trying to involve them more (i.e. with our cookbook, we sent them a personal letter asking them for a "celebrity" contribution, since it would be fun for any child that has them or ever had them to see their contribution). We expected greater response, but we DID get SOME, and we brought this up to the principal, and she said she would ask them for more.
Hope some of that helps!