I should point out that I've had a couple of positive experiences. I wrote a letter to two separate offices, which were not located on the cemetery properties, and received handwritten responses. One even provided a handmade map showing the specific location of my great-grandfather's grave, including the surnames of dozens of graves surrounding his.
Other than that, I've been disappointed with the lack of responses. I've called and was told someone would call me back. Nothing. I've emailed others. No responses. Perhaps they get inundated with requests for this type of information, but it can be pretty frustrating. So in many cases, I have just gone to the cemetery and started walking.
One I visited was Birmingham Cemetery a.k.a. Zimmerman Cemetery in the Carrick area of Pittsburgh. The death registration of my 2nd great-uncle, Jacob Nehren, indicated that he was one of my family members buried there. My sister and I didn't have any luck finding his grave, although we did find a cousin and his wife. It could be that Jacob didn't have a headstone, or that his stone from 1887 had been damaged or deteriorated after all of these years.
However, while reviewing some of the records I had gathered for Jacob, I noticed that his Pennsylvania veteran burial card on Ancestry.com provides details I wish I had seen before. It says his grave location is in Section D and Lot No. 17, and he has a marble G.A.R. headstone.
Time for another cemetery trip!
Note: Digital records for this cemetery, as well as the church records, can be found in the University of Pittsburgh's Library System. Included in this collection are PDFs of "ten reels of microfilm containing a constitution and journal, history, minute books, lists of members, memorial publications, baptismal, marriage, burial, and financial records from 1843-1977."