I've never built a banquette, but my kitchen and dining room is exactly like yours, layout and dimensions. We don't have a wall between the DR and LR however, so we've put a buffet server on the long wall between DR and LR. Clearly, you've outgrown your house. My dining room looks so much bigger than yours because I'm not trying to make it do double duty by storing stuff that should be in the kitchen. The open storage is not doing you any favors of making your space look comfortable and peaceful at dinnertime. Rather than built-ins, consider a hutch or buffet server with some closed storage that you can take with you when you move. Simplify your stuff, and I guarantee you'll add to the function, and you'll feel much more relaxed. There's a principle of elementary education that says if the classroom is disorganized and chaotic, the students will be too. Besides whether a banquette is doable, does it make sense for future buyers? I would ask a realtor before I went any further. I don't like the idea of the banquette against a peninsula with a sink. My counter extends 19" beyond my sink, and I get splash almost to the edge. Seating--we have a 36" x 54" table--a little narrower than most rectangular tables. We put 4 chairs on the long sides. I find that arrangement more roomy than a chair at each end. Extensions pull out from under the table on the short ends for guests. Mine is positioned with the long side along the peninsula, but you could turn yours the other way.

I lost some of my original comment somehow, so ETA this first paragraph: I think it's okay for kids, but tight for adults. We have casters on our table that make it easier to clean and when we had a banquette at our last house it was really handy to be able to roll the table around to get people in/out of the corner. It looks like you're planning a pretty heft table, so maybe casters is something for you to consider as well. *** Is your layout set in stone? I wasn't a part of your previous thread, so I don't know any of the backstory. A pet peeve of mine is when the fridge and dishwasher conflict; in my house everyone wants a drink or snack while I'm putting stuff in the dishwasher. This is how my 7'5"x12'6" kitchen is laid out. Priorities were keeping the fridge out of my work space and no corner cabinets. I debated the dw location, but ultimately, the oven and dw are never open at the same time, so tucked it at the end. Anyway. Just food for thought. You might be able to have a bigger sink if you went this direction...

I, too, think I might remove one of the end sections and perhaps add a small storage cabinet, then do something like acm shows above. Or, if you have room for chairs facing the window, I'd get a table to fill the space as it is and simply not use the spaces that are difficult to use for seating (except maybe for parties). The kids on one end, the adults in the chairs perhaps? You also could look into a custom table made so part of it swivels out to let folks into the back seats. arhaus has a nice selection of refractory tables, which extend by the leaves sliding out from the ends. Not sure if that might be a solution or not. A little cumbersome maybe, but it could work:

I totally agree banguette seating is the worst. IMO you will need to start now thinking about that raised bar ot is a very dated look and in this case really unattractive. The TV in the other room needs to Mounted at the proper viewing height and IMO never above a FP if you have other walls for the TV. I like the besta system from Ikea for closed storag mixed with the TV and some display it creates a very custom look and hides a bunch od stuff to keep eye clutter to a min.