Welcome to the board! You are so smart to make a denim quilt for a boy...it will take anything he can probably dish out. I agree that cross-hatching would look nice. You might also consider tying the quilt instead of quilting it...just not sure if the look you are going for. I'm not sure about what type of thread would be best for tying a denim quilt...perle cotton? Maybe someone else here on the board could help with that. I've heard that a surgeon's knot is the best and that there is a YouTube video for the instructions on how to tie the knot. Your batting will dictate how far apart the knots need to be. I think Warm & Natural states no more than 10 inches for quilting lines, but I would make it closer than that for a tied quilt. Just check the packaging that your batting came in. Try to post a picture when you have it completed...would love to see it!