Removing the pony wall might also cause flooring problems. Do you know if there is finished flooring under there or would you have to try to patch it? Do you have material to patch it? As far as looking at how a different configuration would fill the space, the best thing to do when you get stumped is mock it up. Get our your measuring tape, a roll of blue painters tape and find other furniture, boxes or whatever. Mock it up the best you can. It isn't necessary to duplicate your table -- just get the sense of size and proportion so you can see how it fits in the room. I have seen some narrower pub tables that might allow you to combine olychick's idea with a freestanding table -- put the table up against the wall like a bar and use stools, one on either end and two on the side. You might only have two stools there for everyday if that fits your needs and be able to pull out the table and add the additional stools when you need them. In winter, if you don't use the deck much, you could even turn the table and just enjoy the view. Overall, with just one partial wall there, I like freestanding furniture better than doing a banquette. You can create the same feel and function, but you have a lot more options and can move as your needs or whim change. Got some boxes or poster board?

Overstock is a great source for furniture, and shipping is direct to your home at virtually no cost. They have a really wide range of styles and price points. I've ordered quite a few pieces from them and find the reviews extremely helpful. Here is a link that might be useful: overstock kitchen/dining sets

If it were my table, I’d go with those black chairs on the sides, and upholstered ones at each end for the adults. I don’t feel the clear acrylic chairs do anything at all.

Would a storage bench for shoes next to the door make sense for you? Not sure how high the windows are. Average bench height is 18 inches. I liked the idea of having an armchair or conversation area-- somewhere to have a coffee or drink while someone is in the kitchen. You can easily test the use of this idea if you have a couple of extra dining chairs or accent chairs you can steal from other rooms. You'll want to add a drink or spot table.