Generally, I have a difficult time with GPS, so I might record the general GPS for a section of graves, but tend not to have it for most. I don't have an integrated mechanism, and to stop and manually find and record the data is not something I've managed to date. However, each cemetery does keep meticulous records on plot numbers, sections, etc.
Those I'm planning to keep in a consolidated table under a sortable field so that it can be easily found. For example, under Washington Cemetery, there are sections (mini-cemeteries) like George Washington Mausoleum, and within this, the Mausoleum plots run in building C-60, 4-6 (4th row up, 6th one from the left). The grave markers are more difficult to categorize, as they don't have readable markers, but a good relationship with the cemetery may be able to resolve this to get their numbering system. So I would have a field for the section and a field for the plot location.