Since your son and future daughter-in-law already know what you will be giving them for their wedding gift, why don't you take them with you to the fabric store to pick out their favorite fabrics and their favorite pattern. That way, they will be sure to love it. there is nothing worse than working on a quilt and it not be loved. If the happy couple are involved in the process, they will get exactly what they want AND they will have a sense of the work that goes into making a quilt.