Floor plan design for a semi-detached house 17x10m - Best space utilization?

Hello everyone,
I have been following for a while and have been pondering for some time over a meaningful floor plan for our semi-detached house project, but I just can’t make progress. The maximum possible footprint of each half-house is 8.50m wide x 10m deep, so we don’t have to build a "narrow slit". Desired, if possible, is a staircase with straight steps, either straight or as a half-turned staircase with a landing (I just get a crisis with the steps tapering towards the center and don’t want to have to walk on that for the next 20 years...). The "standard" semi-detached floor plan with guest bathroom, wardrobe, spiral staircase one after the other, then living etc. somehow does not appeal to us at all. We don’t necessarily want fancy gimmicks that waste unnecessary space, but are looking for "the" floor plan with flair. As a layperson, I haven’t gotten anywhere for weeks; every time I think I have it right downstairs, it doesn’t fit upstairs and vice versa. Therefore, I hope for input from you.
We already own the plot; the plan is to rent out one half of the semi-detached house and live in the other. That means we will build a showpiece and one with an okay standard; the exterior should be uniform.
I will just get started:

Development plan/restrictions
Size of the plot: 479 sqm, 23m wide, 20.80m deep
Slope: slight slope to the southwest, approx. 1.50m max over the depth and width of the plot
Floor area ratio: 0.35
Site occupancy index: 0.7
Building envelope, building line and boundary: 3m building boundary (not for garages etc.), no building envelope
Edge development: no (garage allowed)
Number of parking spaces: 2 per residential unit, i.e. 4
Number of floors: 2 full floors
Roof shape: SD 25-45 degrees, WD, half-hipped roof, VPD
Style:
Orientation:
Maximum heights/limits: max. ridge height 9.50m
Further requirements: none

Requirements of the builders
Style, roof shape, building type: modern, linear, simple building form, gable roof
Basement, floors: basement desired, 2 full floors, attic as expansion reserve
Number of people, age: 3 (45/40/2) / 2nd semi-detached half to be designed for a family with 2 children
Space requirements on ground floor, upper floor:
Ground floor: guest WC, wardrobe, large open living/dining area, open kitchen
Upper floor: large children’s room, bedroom, family bathroom, possibly small little study for home office
Attic expansion reserve: studio / guest room / hobby room, connections/drywall for shower bathroom
Office: family use or home office? both
Annual overnight guests: approx. 20 nights, 1-4 people
Open or closed architecture: mixed: living/dining/cooking open, stairs to basement and attic closed, no access to upper floor from living area
Conservative or modern construction: modern
Open kitchen, kitchen island: both
Number of dining seats: 8
Fireplace: yes, if still within budget
Music/stereo wall: no
Balcony, roof terrace: no
Garage, carport: no, 2 parking spaces
Utility garden, greenhouse: no
Other wishes/special features/daily routine, also reasons why this or that should or should not be:
The attic is to be converted by ourselves. If the basement is not feasible budget-wise, a utility room must be planned on the ground floor; however, due to the slope of the plot, we would prefer to invest in the basement. The family bathroom should preferably have a T-layout with barrier-free shower and toilets "back-to-back". Dressing room in the bedroom is welcome, but not a must. If not, at least 3m, preferably 3.50m for a wardrobe is needed.

House design
Who designed the plan: architect from a construction company
What do you particularly like? Why?
- the opposite entrances
- the straight staircase
- the kitchen/dining layout
- glass wall with door to separate hallway/kitchen in the plan for the upper half of the semi-detached house
What do you not like? Why?
- planned without basement; if with basement, access between kitchen and dining (through the house once); with basement, utility room could be omitted
- staircase too much "in the middle" – I would like it somewhat further to the right in the plan to gain more living space
- 4–4.50m window front with sliding door to the garden desired instead of doors, to open the living area more towards the garden
- semi-detached halves not offset vertically to each other (was actually a wish so that the building doesn’t look so massively bulky and you don’t have to pour tons of money into terrain modeling in the garden of the south half – the slope of the plot should easily allow the offset)
- maximum width of 8.50m per half not utilized (only 7.75m)
- bathroom on the upper floor (too small/layout)
Price estimate according to architect/planner: pending (company vacation)
Personal price limit for the house including equipment: 700k
Preferred heating technology: preferably geothermal, if within budget

If you have to make sacrifices, on which details/extensions:
- can you do without: straight staircase, geothermal heating, attic expansion reserve (then the upper floor layout would have to be changed significantly, as no guest room and one less staircase would be needed), T-bathroom
- cannot do without: basement

Why is the design as it is now? e.g.
Standard design from the planner? We still have to discuss, we received the plans in advance just before the company’s vacation started.
Which wishes were implemented by the architect? straight staircase, maximum shielding from neighbors, no run-of-the-mill semi-detached floor plan
What makes it in your eyes particularly good or bad? As a layperson, I don’t want to judge "good" or "bad," I can only say what I like or don’t like. I have largely summarized this above... We actually like the floor plan; I can imagine that with the appropriate modifications it could work out.

What is the most important/basic question about the floor plan in 130 characters summarized?
Would a different staircase, maintaining the entrance situation, significantly gain living space and would the floor plan change significantly with basement and attic included?

At first, one wonders which half will be yours and whether the new neighbor is part of the family? Apparently, one has the A-card here with a complete north orientation and the other the full south side.

You first wonder which half will be yours and whether the new neighbor belongs to the family? One apparently has the A-card here with a complete north orientation and the other the blazing south side.

Hello Katja,
as far as that goes, we haven't decided yet. I wouldn't necessarily call the north side the A-card, since both gardens face west and get full sun from noon onwards. Additionally, the northern part of the property is situated higher, so if the halves of the house are offset in height, that would be the "upper" house. To be honest, at the moment I see us rather in the northern half – a parking space would have to be planned on the northern border anyway and I hate, hate, hate heat in the house... so southwest doesn't necessarily seem desirable to me if I have to shade the whole day anyway. Sun in the garden from noon to evening I find okay... or have I overlooked something important? The new neighbor will not be family but a regular tenant.
Best regards, Barbara

Ok, so if I understand correctly, there should be an offset in height and not in depth? Will it be completely your house and you will rent it out then? Hence the 700k?

Ok, if I understand correctly, the offset should be in height and not in depth? Will it be entirely your house and you will rent it out then? Hence the 700k?

Exactly right.

Personally, I do not like the floor plan at all:

- The staircase is completely in the dirty area, you always carry dirt upstairs
- A straight staircase with this positioning does not allow for reasonable rooms, the house is simply too small for that
- The long way from the kitchen to the terrace is unfortunate and not modern; direct access from the kitchen to the terrace is especially great in summer
- Is the utility room for the washing machine? Even with a basement, it is very nice to have a room for laundry on the upper floor... that annoying staircase run with the laundry is then eliminated
- Upper floor: room for guests and office of 6 sqm... better to combine them, otherwise no one will ever feel comfortable because it is tiny
- On the upper floor, this type of staircase destroys reasonable rooms given the house size...

There is unfortunately a reason why most semi-detached houses of this size look very similar... I am not a fan either, but the design makes everything worse.