Ya'll are thinking too long. A mid thigh jacket really isn't long enough to cause any problems if you don't sit on it. Unless you have a very upright riding position and only a few inches from your saddle to your rear wheel.
I am trying out one of these Columbia "pine orchard" coats. It's kind of a long stretchy windbreaker and I think it's pretty fashionable as well. I like it, it's definitely packable enough to shove in a laptop bag as an afterthought I think.
What bothers me so far: No way to stow the hood. No thumbholes on the sleeves. Pockets are not zippered. The hood impairs visibility too much to use. No reflective accents.
I really like how it covers some of my thighs. I just wear normal leggings when I ride, no shorts so something like this works pretty well for me.