Since the parents are so fussy, I would have them pick the pattern and the colors. It would break my heart if I made a quilt for a grand child and it was shoved into a drawer. I gave my grandson a quilt for Christmas and the first thing he wanted to do was take it to school for show and tell. Also, I think a curvy pattern would adapt better to the patterns that they picked for the room. Squares seem more "tailered". Just my opinion. Sorry this is so long.
Sue