I'll only make a few comments here, as Linn is the real Thanatolithologist, and I a mere apprentice.

We always look for time to visit old cemetaries. Some 10 or so years past while wandering through the Sedgwick Pie section of the Stockbridge (MA) cemetary, we chanced on the grave of Francis James Child; in Maine we dscovered that of Robert P. Tristram Coffin; and we made a special trip to Wilbraham MA to visit the grave of Timothy Myrick who was bit by the rattler on Springfield Mountain.

Rubbings can be done safely; Linn will explain that when she has some time. Photographs can be very difficult, however.

And Clinton, your ideas were put to use in the 19th Century as part of the Urban Cemetary Movement which sought to design these places to also serve as parks, playgrounds and picnic areas -- Mount Auburn, Forest Lawn, et al.