I too collect jeans for quilting, and have discovered that an entire denim rag quilt is extreamly heavy. Now I tend to use my denim for accents, sashings, or borders. One thing you might could do is decide what size squares you want in your quilt and cut your strips accordingly. Then find other co-ordinating fabrics that will fray nicely to alternate with it. That would decrease the heavy weight of your quilt by half.
My sister had me make her boys winter quilts for their beds from denim and bandana's. Cody's bed was done in denim and red bandana's and his brother Dalton's was done in denim and blue bandana's, he was a blue fanatic. They were very cute. We just made some pillow cases by sewing bandana's together, and she paired them with solid colored sheet sets in red and blue.