Memory Book

My husband and I are expecting our first baby, a little girl, in June.  She is the first grandchild for both sides of the family and is already on her way to being completely spoiled.  However, I feel there is a lot she will miss.  While she will have my dad and stepmother and my husband's mother in her life, my mother, stepfather, and my husband's father have all passed away.  (I should mention that I was very close with my stepfather and considered him to be my dad.)

I am looking for a way to preserve their memories and give her a keepsake when she gets older.  My idea is to have family and close family friends contribute to a memories book at the baby shower with pictures, letters, or written memories they have of the grandparents.  

Does anyone have any suggestions for how I can do this tactfully?  By this I mean, I don't want my college friends writing something like "I met your mom once. She seemed nice." I want things that will be truly meaningful from those that were closest with our baby's grandparents.  

Also, does anyone have other suggestions for things that could be contributed to the book?

This is something that is very important to my husband and me.  We both had relationships with all of our grandparents in childhood, and we want our little girl to benefit from as much as possible.