First of all, I think it's really great that you consider all ideas and are open. We have experienced things very differently here and usually lost interest in contributing anything further.
Water/sewage systems stacked are always better/easier - my opinion with some acquired knowledge and a bit of practical experience :)
I already find the suggestions from Hanghaus and Yvonne very good. I would like to "play around" with them a bit more, but despite your explanations, I am still missing some conditions. Please tell me the max. dimensions again, in width and length. 8x12 requires a completely different plan than 9x11. How is the development/building in the south? Do you want as much distance as possible there, or is it indifferent? Your favorite side was the west after your first plan. Is that correct?
Podest stairs ok, or is the straight staircase still the better choice for you? Regarding the straight staircase, I can only mention that we love ours in our long narrow house, but visiting children actually felt uncomfortable and ALWAYS, despite the handrail, also used the contact to the wall for safety when going down.
Making the entrance on the north side next to the driveway to the garage instead of from the east side makes the layout much simpler, especially in a narrow house, but you really have to think that through well, for example that you move the garage door further north and have free space to walk. It doesn't make sense if you almost drive over the first step with the car.
If you like, share more with us. I am sure more ideas and suggestions will come.