I like having the microwave close to the eating area of the kitchen. We use our microwave mostly for reheating leftovers, so having it close to both the fridge and the diners works well. With that in mind, I would choose a location at the bottom right of this floor plan.

Your upper cabinets look like standard 12" depth. I can't really tell what's happening on the peninsula, but perhaps there's a way to build in a space for a microwave on the end, facing into the work area. Another idea is to the left of the sink? Can't realy tell what's going on there.

I can't read your diagram well enough to suggest a place, but that $64,000 question is part of what led us to replacing the cabinets (better layout, but still no good place for the microwave) and ultimately to chose a drawer microwave. We put ours between the cooktop and the table. It is close to where we cook and bake, but also close to the table, where we carry some of the heated food. Some folks suggest putting the micro near the fridge, but I would focus on where the heated things are used. That seems easier for carrying and for traffic patterns. With that in mind, look for a 24" drawer stack and put it in the upper half.

Again, I can't read your diagram well enough to tell, but if that is your fridge on the right and in the corner, it looks like you have a filler, but if you give yourself a bit more room there and use a pullout or put in shelves, you can make use of the space What do you see going on in the right and lower half of this kitchen? Other than a fridge that is somewhat obscured, it strikes me as potentially under utilized space. I'd like to see you explore some layout options that might give you better use of this large space.

I like the MW near the refrigerator and eaters too. I enlarged your layout as best I could and I wonder if the 30" cabinets two down (to right) from the refrigerator might allow a MW. I note you have both 30" upper and lowers, accommodating different MW choices.

Is this layout final? Can you change anything?