If you don't fancy a firework display, what about being turned into a paperweight? Might as well make yourself useful when you're dead.
Tom Sutcliffe wrote about this sort of thing in The Independent, and how his dog almost peed on a pile of ashes - not quite the dignified ending the family might have wanted. At least a paperweight might not get peed on, unless you carelessly leave it in the loo.
A few years ago, a retired RAF officer told me how a former colleague had requested that his ashes should be scattered from a light aircraft. It proved to be difficult to fulfil his request, as the ashes blew back into the cockpit as fast as they were thrown out. Some were swept up with a dustpan and brush after landing; he didn't say what they did with them.

Carelessly throwing ashes around is as anti-social as littering, it seems to me, and not nearly as "tasteful" and romantic as many people might imagine.
Update, September 2018
I've been given a small container with some relative's cremains. The rest have been distributed among other family members and in places my relative enjoyed visiting. I didn't ask for them and didn't want them. I think the idea was that they should go in my garden somewhere. When I'm dead no one in the family will have access, since I'm a tenant, so that'll be that. Meanwhile, they sit on a bookshelf. To prove how illogical I am, a box of my last dog's cremains are nearby, to be inherited by my next of kin. Can you imagine them being passed along after my demise? Well, they won't be my problem, will they?
Oh, and I've just learned that it's now possible to have ashes sent into space.