I am surprised that no one has mentioned Olukai!
I have high arches and discovered these gems about 4 years ago. I wore them ALL day at WDW and do daily until it's too cold. These flip flops were created by a podiatrist who wears them in marathons! They are super comfortable and the BEST I have found.
http://www.olukai.com/
I recommend the Ohana shoe.
http://www.olukai.com/shop/womens/sandals/ohana
You can get them wet, which comes in real handy in rainy WDW days. You can buy them at Takkens Shoes, online or even
Amazon. I highly recommend trying them on. I have 4 pairs of these flip flops and LOVE them!!