I would build a huge memorial the size of Manhattan and place my body in the middle. My casket would be made out of gold, with large pillars five story's tall beaming around it. The pillow upon which I lay may head would be made out of fur from the endangered Amur Leopard.
Seriously? I always say freeze me or burn me, but don't put me underground. If cryogenic freezing is a sensible choice by the time I "die," that's definitely the way I want to go, so I can wake up again in the far distant future. If not, just cremate me. I've seen what happens to corpses after they've been buried. There's no way in hell I'm going to be bug food.
I'd personally choose a cremation as I find a grave site a waste of valuable space and I'll end up decomposed anyway. I do, however, plan to leave the choice to my partner or family in case I die before they do. Some people seem to prefer having a grave to go to in order to keep that memory vivid, or for whatever other reason. In that case, I'm dead.. what do I care.
Classic funeral pyre, like my pagan ancestors before me.
As for trying to obtain immortality or preservation... have my reasons against it, least of all being it is not natural, and that no one should have immortality, ever. People that don't want to decay in the end of it all are just arrogant cowards after all. Let nature take it's course as it should. Yeah, really against seeking of immortality and forms of corpse preservation just so someone won't decay.