After reviewing the program and existing conditions I developed a list of items to address, I’ve come up with what I hope you will find is a unique and effective way of creating better open space and more efficient circulation.
I decided to open up the entry to improve light and space by eliminating the closet area above and creating a two story space. The upper windows will now admit more light and the volume will improve the impression upon entering.
To further enhance the space, I decided to open up the entry to the living room be removing most of the wall including the small angled section near the hall. These spaces will now flow together and open interior views to the back of the house, and now the entry flows easily into the interior hall. You will have to build up part of the floor, and patch or redo the flooring in the entry, but you may be able to salvage some of the boards being removed.
I would remove most of the wall between the hall and existing dining to solve the problem of the narrowness here. If feasible, perhaps you could also enlarge the doorway into the den into a pair of french doors to open up the hall even more and allow light from the south porch to filter in.
My idea is to rethink the way you use most of the spaces, beginning with using the living as a combination formal living/dining room. I think there’s enough room here for a small table (great also for games/cards) and cozy seating area around the fireplace. I would remove the small opening between the dining, while somewhat charming in appearance, it appears they are very low and narrow and really make the space feel closed-in.
I would then use the existing dining room as a new family room. This room would have a new arched opening aligning with the front windows to evoke the original smaller openings, and also provide a sense of separation while keeping the plan open. I would open the wall almost entirely between the new family room and kitchen.
In the kitchen I relocated the laundry area and opened up the room, placing a very wide island in the center. Here I would eliminate the rear door and stair, and placing a new window in the opening you will now have 3 large windows facing the rear yard.
The north porch would make a nice morning or breakfast/casual dining area flowing off the kitchen and family room. I would place a large banquette at the windows to make this a welcoming space to eat or sit. French doors off the end of the kitchen would connect to a new pergola structure (this could also be a screen porch) tucked into the corner. I placed this space here as it’s closer to grade than elsewhere and would easily connect to the existing and possibly enlarged stone terrace.
On the opposite side of the kitchen I would replace the bath with a large walk in pantry. This would allow light from the window to filter into the interior hall and even be visible from the entry. With such an open plan kitchen which is nice, but limits upper cabinets, this would be a nice feature for the house.
To make sense of the changes, I would suggest making the den into a functional and legal bedroom by adding a closet. You may opt to use this is a den/office, but this will add to resale value and keep the marketability of the house. In fact, the adjacent south porch would make a nice en-suite sitting area with separate entrance making this ideal as an in-law/guest suite.
In the rear bedroom I would create a new bath backing up to the existing for plumbing connection and provide a laundry room and additional storage. This space would connect to the south porch by inserting a new door in the existing window opening. You could enclose part of the porch to create a new mud room, thereby providing a family entrance on the side of the house where you already have parking.
On the second floor I would repurpose the interior hall as a new hall bath by slightly and only partially enlarging it into bedroom 2. I created a compartmented bath with double vanity and separate toilet/shower room. You could as an option remove more of the wall, widening the bath at the back and provide a tub here. On the front of the house I would reconfigure the two bedrooms there to accommodate a new closet for bedroom 5, to replace the one lost to make the two story stair hall. Both bedrooms here are larger than the minimum size required by code, so you still have 4 full bedrooms on second floor.
I essentially left bedroom 3 the same, but opened it to a large bath/closet suite in the rear created by attaching a wide shed dormer. Two separate walk in closets are located off a vestibule. Opposite the closets is a new large master bath (basically in the same area as the existing) with double vanity, vessel soaking tub and shower along with a toilet stall perhaps wrapped in the same glass as the shower. The remainder would be a large walk-in closet for bedroom 2. While not required I provided windows across the entire rear of the dormer to let light into all the new spaces, and to improve the rear elevation.
On the exterior I would perhaps as another option maybe replace the roof over the south porches with a new hipped roof to keep this elevation more in character with the rest of the house. If feasible costwise, I would sheath this roof in standing seam metal and reroof the porch and shed on the north side the same. The shed dormer would also be clad in standing seam metal, with these altogether lightening up the exterior elevations and adding a contrast to heaviness of the shingle roofs.
As far as specifying materials and fixtures, I felt there were some anomalies in the existing drawings and I didn’t feel certain about tolerances. So my design I believe will work in the space and provide everything on your wish list. If you did opt to choose my proposal I would offer a few complimentary hours to clarify the dimensions and provide you with a dimensioned plan and more specifics regarding the kitchen layout.