Thanks for the info everyone.
The US firsts will be going on my list of 2013 collecting goals. I have most of the UK slipcased editions currently on order, so those are first, then it's onto the US editions in a couple of months.
One question on the GOT first, I see there's a BCE with the same cover art. Is the BCE also metallic silver? Looking at Becca's photos in this thread the throne seems to be embossed in the first edition. Is it that way on the BCE as well?
I've also seen a few people listing the size of the book in their auctions, so I'm assuming the BCE must be smaller?