How about flying geese gone wild?
http://filminthefridge.com/2012/09/0...ese-gone-wild/
Is that a quick-enough pattern? There are some really nice arrangements online, of which I personally like this one the best. I think it makes for a not too-modern quilt that is ageless. You could use purples and pink and aqua and some neutral with it. I am planning to make this pattern for a co-workers child in mints-aqua-turqouise and beige. If you make the units large enough to showcast the fabric, it is pretty fast, too.
Another choice would be a chevron quilt. Really easy and quick. You could use a modern charmpack and some modern neutrals and build it up with half-square triangles.
I hope you find something. It is nice that you ask your granddaughter for opinion, too!