I just had grandtwins (boy and girl) 3 months ago (you can see their photo I just posted in the Personal Diaries thread--proud grandma here!). After much thought, I decided to make an X's and O's quilt for her, and a snowball quilt for him.
My Grandlambs' Quilts
I chose a focus fabric to use in both, but made his blues and light tans, and hers greys and pinks. You might do an X and O quilt and make one pink and grey, one pink and green or pink and white? Check Pinterest for X's and O's quilts, then find a cute focus fabric to start your hunt.