After being laid off from my job as a carpet mill rep and before finally settling into my present job in retail carpet sales, I had a brief (only about a month) stint in the pre-need cemetery sales industry. I learned a few things about cremation that I didn't realize.
For one, the cremains (the industry term for cremated remains) aren't completely ashes like you might see in the movies or on TV. There will be somewhat sizable chunks of bone left in the cremains, but they can be further pulverized (my apologies; I can't think of a more delicate term) for easier scattering.
Also, check with wherever you want to have the cremains scattered. As someone said, Disney has a rule against scattering cremains in the park. Most private property owners will probably have some policy, as do public parks. I'm not sure about the policy of scattering at sea; I'd check with different cruise lines or even the Coast Guard and see what the policy on that is.
Keep in mind that cremation -- and especially the scattering of cremains -- is irreversible. People are visually-oriented and we like to have a place to come and mourn or remember our deceased. Cremains can be given a traditional in-ground burial or even placed in a columbarium (think a mausoleum for urns).
As for what I would want for myself -- I haven't really thought about it. Most of my family has done the in-ground burial so I figured that is what would happen to me.