I would go with one level on the island as it is huge. I think the corners feel massive but realize they are necessary for the stone. Best of luck.

I wouldn't do two tiers; just the one level.

One level, no bar height, but I would scale back from 6 foot width to no more than five. You're setting yourself up for slab size, seam issues, support issues. Even with a sink, you'll have plenty of room. Not loving the Fridge placement nor the microwave.....what's on the adjacent wall?

The architect thought the ovens corner would help keep most countertop space in one place. I'm w you though not a huge fan, but I also don't want to lose more space.

Fridge...

This looks almost identical to my plan! How funny. I am going with basic double width on the countertop, so likely closer to 4 ft. It will be a bugger to reach for cleaning otherwise. You might consider that. I am doing all one height. I think that is a personal preference, but I really like the aesthetic of one level. Other differences- my range and dual oven are one unit and I am doing a drawer microwave (my mom has one and I love it), leaving space for an appliance garage in the corner.

Also, I think the fridge is ok. Makes for a nice tight work triangle, but it is offset enough to keep snackers who want to rummage out of your way while you work. It's the same place I put mine, and that is why we did it. The microwave will go over on that side of the kitchen for the same reason.

One level, not bar height. Looks too big for my taste.

I am very tall and I find my 51” wide island just barely wipeable from one side IMO 72” is too wide and all one height is always more attractive and also more useable and FYI I never let an architect design a kitchen get a kitchen designer to just go over this design ,I actually don’t see any glaring problems and the corner oven I think is really no a big issue and to be honest I think the island in your inspiration pic is very unattractive and the hood over the stove just a pain to keep clean and really IMO not something I would do unless you have a very traditional home

Here is a wonderful discussion about what people added/removed from kitchen renovation. Maybe this will help.

[https://www.houzz.com/discussions/things-you-added-or-removed-that-you-love-regret-in-your-kitchen-renov-dsvw-vd~4273188[(https://www.houzz.com/discussions/things-you-added-or-removed-that-you-love-regret-in-your-kitchen-renov-dsvw-vd~4273188)

Definitely get a kitchen designer.

I like the placement of the fridge because it is close to the eating area and people can help themselves without getting in your way.

I wonder about moving the microwave/oven to the wall that has no appliances, sliding the cooktop down, and sliding down the fridge so there is a countertop to the left of the fridge for a "drink station" for coffee maker, drinking glasses, etc that is not "in" the kitchen but is in the kitchen.

The most counter top would result with fridge, tall door/drawer storage, micro/oven combo along the stair wall, with a centered hood on the back wall. and a less bulky feel to the cook wall.