I've made a denim quilt and a denim handbag out of old jeans. It's beautiful! There are patterns for these things on the web under: All People Quilt.com.
A jeans quilt is heavy, and ideal for colder climates. I put batting in mine, plus a flannel backing. Quilting it under my 9" sewing machine harp was a slow, wickedly difficult and tough on my arms and shoulders. I ended up doing it in 4 sections because there was absolutely no way I could get half a quilt under my 9" harp. If I had it to do again, I would definitely send it out to a longarm quilter.
On the other hand, I made it for my nephew who was going to college in the upper peninsula of Michigan (Michigan Tech), and he was after me to make an extra warm quilt. This fit the bill, and he loved it. He was also quite hard on the quilt, stuffing it into a regular washer (not an oversized one) when it needed cleaning -- typical male college student doing laundry for the first time! LOL! He used it constantly, even back-packed it out to his camping site to sleep under the stars. Contact with dirt made it get dirty fast, so more frequent washings. It made it through 4 years of college in still beautiful shape, with no fraying or seams coming apart, and then he took it to grad school in Wyoming, where he heavily abused it when he needed to spend days camping in the woods, working on collecting data for this thesis. He graduated from Grad school, and he's still using and abusing the quilt. Of course the denim is getting lighter in places, but the seams remain intact. He says he's going to "love it to pieces", and then have me make him a new one, as he can no longer live without his quilt! So I'd say it was more than worth it.
Make sure you use a heavier needle, meant for denim and/or canvas, got slow with the sewing, and shorten the stitch length a bit to make the seams stronger. I sewed my pieces (the bigger the better) onto a heavy muslin backing, which gave it a bit more stability. That really worked well. I would have liked to do more FMQ on the blocks, but it was so darned difficult to move it under my presser foot. I practically had to compress the quilt sandwich just to get it under the presser foot, which made anything but the most simple quilting all but impossible, but SITD worked well.
Best of luck to you!