Here are some of my favorite patterns (and ones I want to try)... I put the measurements, because you might need some bigger ones for the bigger kids....
http://www.ohfransson.com/oh_fransso...ice-quilt.html (38" x 53")
http://www.modabakeshop.com/2010/10/boxed-in-quilt.html (50" x 50" ) -- This is a layer cake project, but would be very easy to modify for yardage...actually, it would probably be easier to start from yardage than a LC.
http://www.modabakeshop.com/2009/02/...aby-quilt.html 41" x 50". ( I have made this one more than once...goes super quickly with chain piecing!)