In the interest of sharing unique design ideas I will veer outside of the mid-century modern and 1970s era and share some unique plans and ideas.
Over the years that I have worked in the various facets of the real estate industry I have been inside many condominium apartment units in Ottawa. I am always surprised and delighted to see innovative designs that then become inspiration for the "hobby" floor plans that I design as a pastime. One design aspect about condo apartments I like playing with is the idea about space that can be expanded. This is something that is typically impossible with a condo apartment unless an adjacent unit is bought. I am not the only one to have thought of this - here are some examples/ideas in Ottawa.
The Broker I work for recently listed Alanis Morissette's spectacular suite in the Sussex condominium building. Her (now sold) suite was re-imagined from the original plans, but the original design for the building is quite unique. Each floor has 4 standard designs, all corner suites. Yet, each floor has 8 distinct modules with their own separate legal identity. The typical suite is 2 units, but there is the potential to be expanded in to one of the adjacent units - resulting in 3 condos per floor (two 3 module suites and one 2 module suite). I am not sure if anyone actually did expand their suite when the building was built, but the idea is noteworthy!
Additionally, some condo buildings allow homeowners to enclose a balcony for extra interior space, such as at 160 George Street. My Broker currently has a listing for sale in this building with the balcony still open, but I have been inside some of the units with enclosed balconies that have been opened up to the main living space quite successfully.
The Classics at Riviera condo also allows enclosed balconies, but it appears that they must be fully glass so as not to detract from the overall facade of the building. On the flip-side, some units in this complex were built with an enclosed solarium (sometimes called a "sun den") that homeowners have opted to completely open up to the main living space.
Another example at 373 Laurier Avenue East with enclosed balconies. Many condominium corporations do not allow the enclosing of balconies as it changes the look of the building facade.
One building that has always intrigued is the Parkway Terrace condominium at 77 Richmond Road. From the outside the building presents a unique facade with large expanses of glass and deep-set balconies.
The overall layout of the building is very unique with all of the units (8 per floor) loaded on the back of the building, overlooking the Ottawa River and parkway. At the front of the building most units (except the end units and ground floor units) have a second balcony and a solarium space (called a gazebo on the plans). These are separate from the main unit as the building hallway runs between. This unique, yet separate, expansion space could have numerous options. From what I have seen with real estate listings in this building most owners use this space as a solarium, but I could envision it used as a home office just across the hall from your unit.