I had the same thoughts before reading everyone else's posts...The 3 x 6 is more 'standard' and traditional, while the 4x8 would be a little more unique and bring a modern or industrial twist or zing to your kitchen...which I can like with traditional elements. Depends on what you want it to do. And Plllog does have a point about smaller tiles fitting in around things better, but I wouldn't necessarily let that decide it for me. Will one fit in the spaces using whole tiles, while the other will require cutting all the way along? (Remember to figure in grout lines) Even if I liked one better, if the other fit in whole, THAT could sway me to change my mind.

If budget was a consideration for the Eco Cosentino Iron Ore, it will probably be a factor with a real blue granite. Besides, if you want your bs to stand out, I'd let it be the one strong blue element in the room. I'd like the Blue Volga or Blue Pearl because the blues in those are subtle and won't shout for attention. If you have the blue granite picked first, I'd want a calm bs. If you try to have too many stars in the room, then it gets noisy. We have Corian in their Rain Cloud pattern and it has a marble like vibe but it also has some small amount of taupe-ish beige. You would have to see if its soft white works with your cab's paint color. Here is a mellow pic of our counters. There is more color to them IRL but from the distance, they do look like a soft white. I am posting pix of this and linking to another one below to give you an idea of the color range to go with your tiles. You could find the equivalent in stone, but we are happy with the Corian. (try to find the seam.. even blown up big it is well done) I could also see a counter with an orange beige tone in it. That would work with the wood look floor and still pair with your cabs and bs. Here is a link that might be useful: Corian Saffron

I think all the bits and pieces you posted look really nice together! The only thing you didn't post was the grey tile. I would pick a warm grey (no blue in it).

I realized it was granite after I posted and held the notebook closer! lol Using hex tiles would be interesting too, but square would look fine also. Have you glanced through the FKB? Lots of ideas there. Oh..and my manners; I was so busy copy/pasting/looking at photos, I forgot to say your kitchen is beautiful. Here is a link that might be useful: FKB Backsplash Slideshow