I cut size 4XL, adding an inch to the length. The pattern lists 6-foot-2 for this size, and Mikey is 6-foot-4. There's still about 2.5 inches from the bottom of the vest to top of his jeans. (Mikey modeled for these photos at the end of the workday, so his shirt is partly covering the waistband.)
Morgan said she would specify in the pattern that the vest is designed for dress trousers, which sit higher than many men wear their pants today. I'll have Mikey try this vest on with other pants to see how long we need future versions to be. He really likes this one, but I'm not sure how much he'll wear it given how high it stops on him.