Pretty! I think accessories may be the way to go - to do this kind of modest dress without becoming frumpy. I wish this were in fashion, rather than similar skater dresses that are 4 inches above the knee.
Fashion Tips (and a free eBook) here: Do your clothing choices, manners, and poise portray the image you want to send? "Dress how you wish to be dealt with!" (E. Jean) Modest Fashion doesn't mean frumpy!