We cremated my mother for logistical reasons. I don't mean that to sound harsh, but she was in TX when she died and she wanted to be buried in NC next to my Dad. The cost was just astounding to do that without cremation. And we had discussed it before she passed, so it wasn't a decision i made alone or made lightly. So, she was cremated, then we put her ashes in a lovely decorative box that she would have picked and buried her next to my Dad.
A very dear friend of ours was also cremated, at his request and his children scattered his ashes from a boat near a beach that he loved to spend time at.
I would have a hard time "retaining" Mom's ashes, i think. I think it would have made it harder to have some closure. Just my own feelings, of course.