I have been eyeing that skirt/legging combo for running, too.
Susan, my experience with Athleta is that everything fits well, is well made, and they listen to their customers' needs. I have one of their running skorts, but the shorts part are more like underwear, like the inside of running shorts. I wear it, but I'd rather get one with bike-like shorts underneath. There are so many cute skorts around, but many of them are regular sizes and even the size 2s are too big in the waist for me. I do better with xsmall, small, etc. I guess no one will be making petite sized skorts...
I had the same reaction to the back of those pants. I would wear them if the liner looked less, ah, gross.