There are really nice Pentecostal stores that have wonderful modest dresses, skirts etc.
This store is called apostolic clothing and they have 3/4 length blouses, below the knee skirts and dresses.
This is their 3/4 layering top. Really nice. I actually made my own pattern for something like this. Mine is a lot loser though. They also have exercise skirts for swimming in and running in.
I had run into a web site for a Pentecostal church in my area and they had a picture of girls playing tennis with skirts on. Way to go!!