While on Pinterest, I stumbled upon this pattern for a market bag. The pattern allows the crocheter to decide how wide and tall the bag will be.
Rather than following the pattern for the straps, I chained 100, connected the chain to the other side, and did three single crochet rows back and forth. I find that this way of making straps leads to less use-related sag over time.
Below are photos of the bag in progress: