I have cardiac arrhythmia and have actually thought extensively about this since dying young was (and is still) a possibility, and the thought of being able to plan the details was comforting.

First of all, even though it is a bit silly to pump a body full of formaldehyde and put it out in a fancy box for the world to see (and tell how "lifelike" it looks, flying in the face of obvious facts), it serves a perfectly psychologically valid and necessary purpose. I lost a friend in high school while I was away and couldn't come to her funeral, and my grieving process was stilted and made harder by the fact that I couldn't see her corpse. For this reason, whether I'm ultimately buried or cremated, having an open coffin (all the way open, not just at the waist) at my funeral is somewhat important to me. I'd like mine to be mahogany (dark wood just has a sense of dignity) and satin lined, because I think that shows respect for the body. I will wear my sunday best (pintucked blouse and navy knee length skirt) and I will be barefoot. Not only is it ridiculous to try to hide your bare toes from God and man in death, but it's doubly so to put a barrier between the soles of your feet and the nice, soft satin :-> (yeah, I was into this). And by all means, rouge me up and put lipstick on, pale dead faces are no fun to look at.

The funeral itself isn't as important to me. I would assume family/friends would come in on their own time, say a prayer over my body or in a little group, and linger around, telling stories, and grieving in their own ways. It could be in a church if my loved ones wanted, it doesn't matter much to me. Maybe a minister can do a little ceremony and read from Ecclesiastes when they finally close the coffin and pack it off to the cemetery. I think it would be beautiful if everyone brought a rose or other flower too. Music wise, Automatic for the People has a lot of relevant material ("Sweetness Follows", "Find the River", etc.).

I think people who think funerals should be celebrations are missing the point. They are, in their own way, but they are mainly about helping the living transition to their loved one's new state of being (death) and helping close the stage of extreme grief. Or for the dead, about performing the last stage of life they would be able to control (if they are me, at least).