The height you'll want your half-walls depends on the furniture you plan to have in the room, how tall you are, and just how open you want the room to look. I've seen halfwalls everywhere from 24 inches to 72 inches high! Personally, both extremes bothered me. I'm tall and I'd probably trip over it if I lived in a house with a 24 inch high halfwall. On the other hand, one has to wonder what the whole point of the 72" high half wall was. It was just high enough that any dust that collected was visible to us tall folks but one really couldn't look over it however noise from the other side flowed over so one couldn't really use both "rooms" at one time. It would have been so much better to use a full height wall and maybe put in some interior transom windows if one wanted natural light from one room to reach the other. So, I probably wouldn't choose to go under 36" or over 48". BUT - you really don't have to make your decision immediately. Since half walls are not supporting walls, reframing to make them taller or shorter is a piece of cake so why not take a wait-and-see approach. Have the builder frame them at 42" and then, before any electrical wiring is run or any sheetrocking is done, take a blanket or something over to the house and throw it over the halfwall to give it the look of a solid wall. Then decide for yourself whether it seems too tall or too short. If it is too tall, the builder can lower the wall easily enough by taking the top plate (2x4) off and cutting each of the studs down a little then putting the top plate back on. Or he can make the wall taller by adding another layer to the top plate. It is probably a tiny bit easier to make the wall taller than shorter but neither one is a big deal... as long as you do it before sheetrocking and don't keep changing your mind! Trust me, you're going to have PLENTY of other things to stress over before your house is done so don't waste any stress hormones over this one. ;-)

I could reverse them, but then is it strange to have the toilet RIGHT on the other side of the dining room? (And to have it across from the front entry door?) And, it'd mean no mirror above the sink. I'm hesitant to do the pocket door for sound and privacy reasons. A swing in door absolutely won't work (no room to turn around to close it). The window is a high window about 5 feet off the ground and only 2' x 2'. It'll have a decorative stained glass insert that you won't be able to see through. It's already all framed in - no changing it now!

Whether to do a passthrough, half-wall, or full wall all depends on how you want the two rooms to feel and function (both separately and together). So, I cannot tell you what will work best. However, my brother recently renovated his kitchen (nearly finished) and changed a full wall to a half wall between his kitchen and dining room. He tends towards more informal gatherings and he wanted to help the small closed-off kitchen feel larger and more open to the house. He does not like upper cabinets and with the remodel was able to acquire additional lower cabinets to make up for the lost storage. He has no stools on the dining room side of the half wall, though the granite does cover the top of the half wall. (In fact, the dining room is simply too narrow to accommodate a table and chairs and counter seating.) His new kitchen feels very open and light (the dining room is on a corner and light floods in from two large windows) and he is extremely happy with the result. Your inspiration picture is very lovely. The detailing on the window is beautiful and could probably be duplicated through wood trim on a pass-through if you would be interested.

I bought a 1 1/2 story house in 1984. The upstairs was finished on one side only - a bedroom that had sloping ceilings on both the front and the back. We chose to put a full dormer across the entire back of the house and finish the 2nd side of the upstairs, adding a bedroom and ensuite bath. No problem with the foundation holding it up - it was already holding up a 2nd floor, just without a dormer. But this was a dormer across the back - not one on the front trying to make the house look like a true 2-story colonial. In early 1985 when we started our remodel, just adding the dormer cost $20,000. That was 33 years ago! I can't imagine what the cost would be today. And that was just for the dormer. A realtor bought a 1 1/2 story house up the street from me last fall. He has turned it into a 2 story house, front and back. He paid $434,500 for the house and is now asking $814,000. He did a very cheap remodeling job. Look at the cheap vinyl windows, the horrid shutters (vinyl and too narrow). He tore out the lovely, established landscaping and put in something cheap and generic. Yes, the existing landscaping needed some pruning - older lady could no longer keep up with the yard - but that tree hid that very prominent chimney right in front. I'm sure he expects to make a ton on this house, but he also spent a ton on the house, even if he did not remodel it to the standards of the neighborhood (in my LCOL area, this is a very desirable, high priced neighborhood). BEFORE: AFTER: Perhaps this info and these pictures will help with your decision.