This is the view from the living room, looking across the wood part, to where the slate will take over and continue in the entry and down that hall:

I don't see the need for two table seating areas so close to each other - just keep the dining room and use it more. So, I like your idea of making a triangle-shaped pantry against that angled wall. I would probably just put the Fridge on against the bottom wall of it with the door to the Pantry next to it. The right side of that wall is then a nice blank wall perfect place for a bar area, artwork, sideboard, or other item. I would then: put the range on the left side of the U; make the left side of the island completely cabinetry (no overhang) so you can have a prep sink at the top left corner of the island. The seat that was there moves to the right side of the island so you have seating on two sides of it; put the MW in an upper on a shelf, or a drawer MW below the counter, next to the range on the side nearest the fridge/pantry; completely delete the right wall of the U so you can make the island at least somewhat bigger whether you remove the wall entirely or not; put the ovens to the right of the sink; and put the DW between sink and ovens IF you need an obstruction-less secondary prep space (between sink and range) more than an obstruction-less baking zone (between sink and ovens. I don't think a half wall is going to do much to hide kitchen mess for you, but if you put the ovens next to the sink like I recommended at least the cleanup sink rack, mess etc. would be hidden from the entrance. However, a half wall with some nice trim, maybe some posts, etc. would provide an elegant separation between the DR and Kitchen plus some nice display space. Going without would give you a bigger island. It's up to you.. Anyway, HTH! I love interesting spaces like this and I think you can have a phenomenal kitchen.

I would run the veins long-way along each section of counter. So on the right in your picture the veins would run up-down and on the top of your image and island, it would run left-right. So the veining would flow around the corner of the kitchen. I think this is how it is normally done, instead of all the veins going the same direction across the kitchen. I think it would be weird for the veins to run along the short length. I'm trying to find a good example picture, but I'm having trouble finding something that shows it well.

I think this plan is pretty good. Trust your tile guy (but have him do a sample first). Remember that stone (especially marble) is much easier to cut than tile. It is softer and you don't have to worry about the middle being a different color. It's going to look nice. I would have ordered the tile trim but I think this is probably better when you have two very different tiles--you don't want too much fussy stuff going on. Love the tile samples...nobody is going to think twice about your tile interface. (Schluter is usually kinda ugly.)