How 'bout...
Just get a simple rectangular headstone.
Quilt yourself some removable covers for it.
Maybe... one for each season. Then in your will, whoever gets most of your remaining $$ (what you haven't spent on fabric) has to go and change the cover each season.
Might guarantee you three "visits" the first year, at least...
And the covers of course will be washable.
And unique!
:idea: