i am not a fan of ritual in general, and i particularly despise how death rituals (that i am familiar with) are so often steeped in religion, capitalism, and spectacle. not to mention... they don't typically seem like celebrations.
and for sure (to agree with other answers), the typical western way of burying the dead is absurd, imo. even cremation seems wasteful, if much better than burying a preserved, protected and falsely beautified body full of poison.
personal anecdote: about 16 years ago my wife's brother died unexpectedly. his entire family converged at his mother's home in nyc for several days, coming mostly from haiti and montreal (which was difficult, as nobody had any money to speak of). the main reason everyone was there was to have a typical religious ceremony; his mom was catholic, though he was a hardcore atheist. but in the few days we were all staying in his mom's apartment (25 or so people camped out all over the floor of a smallish apartment), we laughed, cried, cooked, played, danced, and just got to know each other in a very tender and loving atmosphere. it is one of the best, and most emotionally fulfilling, memories of my life. i cannot imagine a better celebration of one's life. fuck the church service. then my wife and i took his ashes back to the west coast, had a roaming party with all his friends, and scattered the ashes in all his favorite wild (and not so wild) places.
i share dot's thoughts about what i'd like to happen to my body when it has expired. and actually, where i live, i probably could make myself wildlife food pretty easily.
i have no idea how accurate it is, but the viking ceremony i have always read about has some appeal, though burning a good boat seems unnecessarily wasteful.
grief is a very strong emotion, and everybody processes it differently. i think a celebration of one's death should have room for, but not focus on or spectacularize, grief.
i have yet to go to one, but i have heard many times about "death cafes", informal gatherings where death is the topic of discussion. sounds like a pretty good idea, at least potentially. especially given western culture's typical ways of dealing with it - trying to avoid it at all costs.