My cat is still young so I don't have to worry about this for several years (knock on wood), but I love her like she's real family. She's been the only constant in my life for years, and I know that when she passes I will grieve deeply. The question is, what to do with her once she is gone? I move around a lot so I would feel uncomfortable burrying her at my residence when it happens, or anywhere else really. Then there is the question of cremation... what do you do with the remains? Is it strange if you keep them in an urn or other container? Is it more appropriate to scatter them or... what would you do?
I chose to get my cats cremated, and then have the cremation facility dispose of the remains for me. As much as I love my cats, I don't attach any particular significance to their dead body (I feel the same way about my loved ones). Once they are dead, everything that made them special is gone and I am left with just a lump of tissue. I don't feel any particular need to keep their grave close or their ashes on my mantle.
But that is my choice, based on my beliefs. If you are the kind of person who feels it's important how a body of a loved one is disposed of, then I would recommend cremation - most because it's difficult to bury a body deep enough to protect it from scavengers. And if you had your cat euthanized, the scavengers could get sick from leftover euthanasia solution. Also, burying an animal on your own property - even a cat - is often illegal in many cities.
Whether you choose a fancy urn and keep the ashes displayed, scatter the ashes somewhere special (like a bird or wildlife sanctuary), or choose something else, it's really about what would mean the most to you. Body disposition is really about providing closure for the surviving loved ones (i.e. you), so it doesn't matter a darn bit what someone else would do. I told you that a practical solution is what works for me. Others feel like they need to set up a shrine or memorial. Still others like the symbolic "setting free of the spirit" by scattering the ashes. These solutions are the best ones for them, but maybe not for you.
If you are undecided when the time comes, I suggest choosing cremation with the ashes returned to you, You can always take your time and decide later, when some of the grief has worn off.