What is the best website for beach-appropriate wedding atire?

For whom? For the bride, the groom or guests? If you want to get an eco-friendly summer dress – casual but pretty and inexpensive – check out http://www.thegreenbrideguide.com/lookbook/lookbook/attire/gowns.html for some ideas. I recommend organic cotton or hemp. Synthetic fibers are hot, sweaty and not sustainable. Good luck!