I know this isn't all white, but it has a lot of it. The darker fabrics are all tiny red or raspberry colored flowers on black. I made it for my Mom but she said it had too much white for her (she had a lap cat)

I saw on a decorating show lately about decorating with white and they said to use all shades of white and off-white to pull it off, not pure whites. And to use different textures. It's too cold and boring. Tone on tones would help with the "texture" needed. A simple pattern of squares made of various width strips set on the diagonal would probably work.

A log cabin with whites for the light side and a lot of various pinks for the dark may work.

to Baloonitic ... This is really very striking, and must be more so in person.
I hope your mother is not really rejecting this gift just because of the cat? My dog loves to get on the bed when there is a quilt on it, so I am making her one to go at the bottom of the bed out of the "I don't know why I bought this" material! Maybe this will work for your mother.

I'd do a "Yellow Brick Road". The pieces are relative large and the blocks make up to 9". It's fast and easy and would show off different shades of white. If she wanted some pink in it you could always applique some pink flowers on the whites.

Oh, Thank you all for so many good suggestions. This sounds like a good one. I plan to take my sister shopping in my stash, take her to a LQS, offer her the pattern suggestions you all have shared and JUST DO IT!
At this point, I am leaning toward log cabin, rail fence and irish chain. I will leave it up to her. As for the great suggestions for the quilting, I must admit that that is my weakest point! I usually do the least possible, by hand, machine or even (gasp) ties.

What about the ten minute square with just a little pastel pink in the middle? I have tried this square with different sizes of middles. Might not take too long. If you are HQ, I would not use white on white designs. Those are hard on my hands and my needles. Good luck.

This is what I was thinking.

I am not sure how to do this so looked up the one I remember and saved. it was
posted 9-17-10 by miss_ticky2 it is whites and tan in a crazy quilt pattern
Really beautiful

My daughter and I recently made a quilt using all white, white on white and off white fabrics. It was elegant. It was similar to a turning twenty pattern. Nothing fancy.