I started out wearing long (9-10 inch) shorts. Funny, because I am only 5'1". Now, I have shorts that are about 7 -8 inches and very compressive (Terry Bellas), which I wore all of the time, until they were so hot and uncomfortable on my trip to Spain, that I bought another type. Now I also have 4 pairs of the Shebeest S Pro shorts, which are about 6 inches and less compressive and lighter, but have that great wide/flat waist. I absolutely cannot wear shorts any shorter than 6," probably because I have big quads and a butt, while not huge, is not entirely firm. Short shorts make me look much more "jiggly" than I am. It's the same reason can't wear boy shorts style underwear or swim attire. The things just ride right up my thighs and settle into my crotch. Every time I hike or nordic ski in the winter, my lovely Ibex boy short underwear are riding up. They keep me warm, but boy, do they annoy me.
I tried the Terry Bella short-shorts (maybe 4-5 inch es) and wow, they hurt like hell. It's the same chamois, but the shorter length did something to the way they fit me and into the garbage they went... thankfully, I bought them at half price.