April,
The paper I submitted for my Master's degree discussed the evolution of interpretation at the Lincoln Home in Springfield, IL and in the NPS, and came across several sources to expand my paper. One written about Colonial Williamsburg by Carey Carson and the other on Historic House Museums (author I can't remember right away, but will provide off list if you'd like). I looked at interpretation and how it changed as perceptions about history and about historic sites changed. Don't know if that will help you, but I thought I'd offer.
Jim Sturgill