I've been through this myself, and helped others in similar situations. I know people don't like talking about death, and for some having these kind of pre-planning discussions is depressing and uncomfortable. But guess what? It's even more depressing, uncomfortable and anxiety-ridden for the folks who are left behind, playing the last minute guessing game, trying to make all the pieces fit.
So, as a pubic service announcement, if I am in the position where I must make your final arrangements, and you've failed to discuss this with me ahead of time, I'll be invoking the new default setting. You will be cremated at an unannounced time and date and your ashes will be placed in the ugliest urn I can find. That urn will then be "accidentally" donated to a rummage sale. I won't bother publishing an obituary but if I'm not distracted I may mention your passing on twitter.
If anything about that horrifies you, please feel free to have a talk with me, so we can plan something more suitable. Otherwise you've been warned.
And if you're at the age where you should be thinking of your own arrangements (which, frankly, in my mind is as soon as you're an adult, but your mileage may vary), please take the holiday season to have the discussion with your nearest and dearest. Talk about living wills, about organ donation, and about what you want to happen when the time comes. Put your wishes in writing if you can, and make sure multiple people have copies. Planning ahead is a gift that you give the ones you love, to make their lives easier at an incredibly difficult time.