In the last few years, lots of greats (Nike, New Balance, Patagonia) have introduced longer workout tops and tunics that can be coupled with shorter gear to create the ideal modest gym clothes. These tops fall well past the waist and generally over your bottom for maximum covered. You get all the performance value too - these tops are sweat-wicking, to keep moisture away from your skin to give you a lighter, more enjoyable workout.
I just bought the New Balance top below for my summer runs and will layer it under a thinner running shirt, to ensure I'm modestly covered and comfortable during my summer workouts!
