Question--will you really be able to get those Ann Sacks tiles delivered in three weeks? If not (my experience is that some of this stuff takes 4-6 weeks), maybe you could slow down--and wait until all the materials are in. I know what you mean, though b/c we are building and we want to get it all done at the same time so that once we are in, we are done! But, it might be worth just giving it some time. All of that being said, I think either of your choices will be wonderful. I would probably keep it neutral with either marble or cream/white subways.

Just my 2 cents, but i'm not a fan of the smallish glass tiles as I think they're a current trend, and not a long term item. Have you considered, or even looked at subway tile? 4" x 4" tile on the diagnonal with a possible border is another possibly. I'm more traditional so not into trends at all.

Based on the detail I can see in your picture I agree with your thought of gray or beige backsplash. Do you have a picture from another angle? Or of the countertop without glare? A mosaic the same tint as your countertop could work (hard to tell from your picture, but pewter or fog might do the trick http://www.walkerzanger.com/collections/products.php?view=mat&mat=Ceramic%20and%20Terracotta&coll=6th+Avenue) Or keeping it simple with back painted glass backsplash Could try other shapes as well, but I'd stay away from subway tile.

To be honest, we have had a lot of problems with Compaq. I would not recommend them. I do like the material but it has been a headache. We also just got a new piece of quartz that was supposed to match and the new one has black dots which was does NOT match any of the other pieces. They claim that it is supposed to have black dots but we would never have ordered this material with Black dots that does not match our other pieces. We are really disappointed. We are in the south Florida area.