Picked up a new Space Gray MacBook Air yesterday at Apple Store, I may have gone with Silver if they had both in stock, but for what I purchased (16GB/1TB) it was looking like it was difficult enough to find a Space Gray and I'm happy with it.
I think it looks sharp, don't anticipate problems with scratching or anything like that. It won't be taken out of the house (probably ever) and in fact it won't really be used nearly as much as many are for those who use these as their primary computers.
I do agree that the color choice is more significant for a laptop, much more than a phone which for most people spends its life in a cover or case of some type. I've had various color phones and don't even think about or notice the color since it's only slightly visible on the back around the camera lenses.