I can't imagine how I would feel if my quilt was ruined by a cat! But you're right, accidents happen and can't be un-done.
I made a chevron quilt...not queen size, but a large throw quilt. Piecing it was amazingly fast and enjoyable.
It uses two fabrics, but you could use more. It's also very patriotic, but you can use any theme.
Here's the link.
http://www.quiltingboard.com/picture...n-t252879.html
Good luck with your quilt, and I hope your sister is recovering fast!