With all due respect to LL, I disagree that just because an island is movable, you don't need to worry about its dimensions. If it's over-sized for the space - in other words, doesn't allow comfortable aisles - you'll need to move it so often that it will be a PITA. It's not going to be a light little thing that is easy to shift, it's going to have some weight to it, especially if it has a stone top and has additional weight from the items you store on it. I would find an island that fits the size so that you only need to move it on rare occasions, not on a frequent basis. I drew up 2 variations of the U lay-out with an island and banquette seating. This allows you a 27" x 44" island, which I think is large enough to be useful. The aisle measurements are fridge (handles included, est 35" deep) to island counter, island counter to sink run counter, range run counter to island counter, peninsula counter to exterior wall, peninsula counter to table and table to wall. Oops, I forgot to adjust the above plan to show two 24" cabs to the left of the range. I do show that on Plan A-2. The plus with the banquette in this plan is that those seated on the bench can slide in and out without asking someone to slide out first. The downside is that clearances between the table and top and bottom walls is a bit tighter than recommended (44" for walk-behind aisles). You could center the banquette and have nearly 39" at each end instead of slightly off-center as I drew it. Here's a variation of the above. This plan creates an L banquette, which allows room for wider aisles at the top and room for a 30" cabinet next to the table. You can use this as your Command Central. The downside is that the person seated in the lower right corner will need to ask someone to move in order to get in and out. Some people are okay with that, others hate it. Here's an issue with both plans. It's a heck of a long hike - more than 11' - from fridge to sink in this plan. That definitely more than is recommended by the NKBA and for good reason. I'd like to see a water source between fridge and sink. However, the island just isn't long enough for a prep sink, IMO (I agree with a wise CMKBD, whose name escapes me at present, who advises against a prep sink in an island less than 60"). One option is to switch out the 36" corner Susan and make it a 36" corner sink cab for a prep sink. But ... then what purpose will the island serve? I agree that it would be nice to have a little more counter to the right of the sink, say by making that corner a 36" Susan cab, but that reduces the aisle between peninsula and exterior wall to 39". If there wasn't an in-swing door right there, that could be doable but since there is, I think a wider aisle here would be better. Which is higher on your wish list: an island or counter seating? If the former, I think Plan C is the better option for you. It has a good flow plus it leaves sufficient room for a kitchen table; no need to resort to a banquette.

I'm not sure which layout I like best yet, and it might not be any of them. Here's why. Are you really going to spending your entire time entertaining at your sink? Point being, I actually think an island sink is in the way of any entertaining (and any view) and really limits your prep space. If I'm entertaining, I wash dishes at the end of the party. I try to load dishes into my dishwasher as the event progresses, but I like the island clear of anything since that's where people tend to gather. Having a sink in the middle of the entertaining space gets in the way of all the action. Add dishes that are waiting to be washed will just add to the mess. Having a clear island gives you a TON of prep space. Your prep space in all 4 of those options above is really choppy. So, I'd put your micro drawer in your island. You could also try putting either 1 or both your ovens in your island. Put your dishwasher and sink in your perimeter.

Here is an idea for you. Minimal framing and it would open up the kitchen space: 1. tear out the pantry and the internal walls of the powder room and the powder room sink. 2. Frame in a pocket door and solid wall for the powder room, reorienting the door. 3. change up the sink in the powder room for a very minimal thin sink hung on the wall across from the toilet and change the toilet to a round bowl that takes up less space. 4. Frame in a new wide archway to the dining room that is next to the stairwell 5. eliminate the existing door to the dining room 6. counters along the exterior wall with sink under window and cooktop on exterior wall for venting 7. countertop along dining room wall anchored by a double oven 8. refrigerator and pantry along opposite wall from sink - can make pantry depth of standard depth fridge to save on appliance cost - pantry can be doors with shelves all around or cupboards with pull outs. 9. island with 42" space to sink area and aligned with dining room opening 10. not to worry about work triangle with fridge because island becomes prep space see sketch:

Here's a photo of the dimensions of the L shaped island. We'll ask an installer whether this can support a porcelain or quartz slab countertop on its own or if it needs brackets.