These look great! I have made something similar out of horse feed sacks and chicken feed sacks. I have made the handles out of the bag material, but it's not easy to attach them and have the stitching come out looking neat. I like the idea of grommets and rope. If your handle starts to look ratty you can take it off and wash it or even replace it with no trouble.
Your bags have the look of paper bags, with the folds/creases on the sides. Did you just fold and press it to make the creases? Also, did you start with 2 rectangles and stitch sides and bottom then match up the side and bottom seams and stitch across to box the bottom, OR, did you cut squares out of the bottom corners and stitch the cut edges together? Sorry to ask so many questions, but your bags look so nice and sturdy that I'd like to replicate them. Would you mind giving the dimensions of the pieces?