Hmm...I guess I imagine an elven gown would be flowing and not too wide; made of light fabric, maybe with sheer, draped overlay-ish things and really delicate, intricate embroidery in white-on-white or silver (leaves, vines etc) and a twig/vinelike tiara? Probably a simple "scoop" neckline with embroidered trim or maybe an underlayer, like a chemise, and long, maybe sheer, sleeves that would come to a point or bell out. Something really graceful & ethereal.
Hobbits? Yes, something more country-ish, in a warmer tone of white, maybe sort of a renaissance type thing with a lace up overdress over an underdress & a fuller skirt, and maybe with other colors incorporated ... maybe some golden yellow? And of course, a garland of fresh flowers!
What about dwarven brides? Beribboned beards?
