As someone of taller than average stature (5'9.5") with broad shoulders and no hips who carries her weight in the belly, I have to be careful with maxi dresses. I love them, but if they don't have a visible waist, they don't love me back. Even a gathered waist isn't always enough since I'm also pretty busty and have to go up a size to give the girls enough room. This is also why I have a large collection of belts and scarves. I need to accentuate my natural waist or else I look lumpy in unflattering ways.
Summer in Seattle isn't warm every day, even when the sun is out, and as such I paired the dress with a light weight cardigan. To keep things airy and light go with a light knit with a wide weave. Added bonus, it makes the dress more work appropriate. Since the cardigan is light and stays open, it doesn't make you look wider than normal. If you are worried about things like that, you could also belt over the top of the cardigan.
Accessories are how you really make or break an outfit. Instead of being a standard sprint outfit, we want this to be Megara. As such keep to a Greek style. Gladiator sandals, simple knots, geometric designs and gold instead of silver. I tossed in a Pegasus clutch becuase how could I not? It was adorable. Nude lip, smokey purple eyes, and your hair pulled up in a pony tail and voi la! The job is done.
Thanks for coming by, it's been a real slice.