I think it is a wonderful idea to create something from your grandmother's wedding dress. While I haven't made one myself, I've heard about making quilts from meaningful squares of old clothing items (i.e., infant clothes, vacation tee-shirts, bridesmaid or prom dresses, etc.). I've also heard about a woman who made pillows from her daughter's infant dresses (the ones that were too cute to just get rid of). She made them for her daughter who is now a teenager. Depending on the size of the wedding dress, you could probably make several pillows for different family members. Another idea would be to make a ring bearer pillow for use in any future family weddings. It would be a nice way of remembering your grandmother at a family event.
As far as the craft/sewing part, you might try posting an ad at a local fabric store for a seamstress or someone who enjoys making crafts such as these. If you are interested in the quilting idea, you you might be able to find someone at one of the local quilting stores who would be willing to make it for you or know someone who would. Good luck.