As the living space of the Minami sisters in a show called Minami-ke, the Minami Residence (aka Minami Flat) is by far the most viewed location in the show, and the only one besides the Other Minami Residence to be more than a generic location design. It appears to placed in a lightly-urbanized part of Japan, neither urban nor truly suburban. Per Minami-ke Episode 7 (Minami-ke Chapter 36), it is also not in Nagoya.
The manga is extremely vague about the room structure and location, giving only random tidbits of information. However, the anime seasons, out of necessity, have considerably more detailed location designs. While the design is continuous between seasons two and three, it changes radically from season one to season two, when production switched from Doumu to Asread.
Because of the need to maintain consistency with the manga while simultaneously having freedom in a wide variety of design choices, the differences in design represent an interesting mixture of enormous differences and shared details. For instance, both designs include a square room with a kotatsu and a TV. Both designs place the flat as a whole on the corner of the square building, but the season one design has it on the right side on the third floor, while the later design has it on the left side on the fourth floor. The season one design has prominent stairs just outside the front door while the later design incorporates an elevator in the center of the building. Finally, Chiaki and Kana sleep separately in season one, but share a room in later seasons.
In both seasons, the balcony from Kana's room faces roughly east.
One detail that can be gleaned from Minami-ke Chapter 22 is that Chiaki's room has a sliding door, which it does in season one, but not in later seasons.
Most closets are guessed from the positions of the doors. Only Kana's closet in season one is ever seen open. The door from the hallway to presumably Chiaki's room is never seen open, and is missing from the chase scene in Minami-ke Episode 01. In Minami-ke: Okawari Episode 13, broadcast version, the front door opens the wrong way, a mistake which is corrected in the DVD version. Chiaki's bed is the one farther from the window in the later season designs.