I don't think your room is long enough to accommodate both spaces. Would be very cramped with dining table and living furniture. Most dining room are at least 11ft wide.

How big a table are you talking about? At 9x11, the existing dining room is tiny. You are limited to a 3x5 table. I doubt you could get a similar size table in the great room. A dimension isn't given for the fireplace, and you'd want the table further from the fireplace than from a wall. Table alone leaves you 12'6" of living room space, then subtract 4-6' for fireplace space and your living room space to 6 or 8 feet. If you want to do the combined living dining, you may want to do away with the fireplace.

Overall this seems to be a pretty small foot print. I'm guessing 750 sf? Even in the breakfast area, I doubt you could fit more than a 2 seater there. You may be better off to make the counters L shaped (back and left wall). You could then probably get an island in for seating. Can't really tell since there aren't dimensions.

You could enclose the back porch and make it into a dining room. It should have plenty of room for your table and chairs. It looks like this plan might already have the area under roof.

Then you could make the existing dining room into an office.

BTW, I don't like the little powder room off the entry. That's an odd place for it. It seems very out-of-the-way and far, far away from the action area in your kitchen. I'd trade its space with the laundry room, and then reconfigure your master closet/bathroom/laundry.

This looks like an adequate home for two. Yes, you can fit a dining area and a seating area in the great room, It might make more sense to wall in the stairs and move the fireplace over to the stair wall, making a seating area around the fireplace. Or you could leave the stairs open and just set up the dining area next to the stairs. The house is not so big that you'll have a long walk from the kitchen.

How many folks would be sitting in the seating area, and what sort of furniture did you have in mind?

I think you would be hard-pressed to put a dining area and a typical-sized seating area in the Great Room. But in any case, no way there could be a functional walkway too.

Just did a quick sketch based upon a 21.6 x 17 room and added some standard sized furniture. I think it will be tight., but if you could stretch the middle section even 2 to 4 feet, it will work increasingly better. Maybe even better it you switch the fireplace and the stairs.

I would agree with the other posters-- the space will be pretty tight. In my own search I had come across another plan that had a similar intent. I know this is more sq. ft. than you are looking for so disregard the parts that don't apply, but I think the circled part of the kitchen-dining-family room gives you an idea of dimensions. This designer did 29' for the dining + family room, which seems "cozy" in the pictures. They get a little more open feel since they have no walls in the whole space (kitchen-dining-family). The link below has some pictures of how this plan looks when actually built.

Here is a link that might be useful: Link to kitchen-dining-family look