Yep, just listened to the SYSK podcast on headstones. Happened to also be the first time I walked through this cemetery. Walked around it a lot but not through.

Materials wise limestone and sandstone type materials do not last. Marble is better vertically but will be completely illegible if left horizontal. These barrel vaults last but not their markers are hard to read. Hands down the best material is the dark gray ones which, after a little internet searching, I am pretty sure are slate. Unfortunately the markers often fall over, so even if it lasts it probably isn't in the original spot. I'd recommend a wider base slate headstone or a combination of vault with slate faceplate.

Also weeping willows were the most popular imagery here although there was at least one hour glass and one I am interpreting as an eternal flame. Pretty sure this eagle thing is from much later.