I'm okay with SW's design; looks "gypsy witch" enough to fit the bill, without sticking out in a crowd like a cosplayer. I'm still very curious how they'll portray the origins of her powerset, though; I'm thinking (and hoping) that they'll go full-on witchcraft, "Charmed" style, but we'll see.
As for QS, the costume itself is a fair enough representation of the blue suit without going all four-color spandex. The hair is, of course, off-putting for those of us hoping for the iconic platinum look; but here's my thinking on Joss' point here:
The Maximoffs are supposed to be twins, so Joss probably figured casting two people who look enough alike to be twin brother and sister (and Aaron and Elizabeth fit the bill pretty well) would work, while giving them the same hair color would be more logical than giving them different colors.
Still, the silver hair could come into play by the end of the movie....it could be explained as a by-product of the speed factor (i.e., causing Pietro's body, or at least some parts of it like his hair, to age more rapidly --- although that obviously creates a MAJORLY lethal side effect and shortens Quicksilver's likely lifespan in the MCU), or simply just have Pietro dye it by the end to give himself a look distinct from his sister.
