Take your inspiration from buildings made for various purposes. In your search I would consider:
- Community arenas
- Day schools
- Boarding schools
- Frat houses
- University dorms
- Ski Resorts
- Fishing Resorts
- Soviet cold ware era apartment houses.
- Israeli Kibbutzes.
Each one has a different impact on how people live together.
Also, a northern diary farm until recently would have huge barns. A modern one is around 100 x 160 feet. This is for the dairy operation run by a single family with a few hired hands.
My grandfather's hop kiln was 200 feet x 90 feet, 3 floors high, with the bottom floor the hop bailing room, and storage for bales, and the top two floors being hollow floor drying rooms for the hops. (Hollow floor: 2x4's on edge 1" apart covered in burlap. Heated air was pushed through the floor to dry the hops.) Now, he had 8 full time hands, and seasonally would hire 30-150 migrant workers. Later, as hop picking became much less labour intensive. When I worked for my uncle the whole harvest may have 30 people. Still some migrants. There was a kiln like this on every hop farm -- typically 40 to 200 acres. Size would vary according to the farm.
Every Canadian settlement also had a grain elevator. Sometimes privately owned, more commonly owned by a co-operative. Farmers would buy a share in the co-op, sell their grain to the co-op, who in turn would broker the sale to the rail company or later the Canadian Wheat Board. Grain elevators are huge
This illustrates a different form of communal invovlement -- where it's not owned by the community, or an individual, but rather by a subset.
The point of these two examples show that large buildings were not necessarily communal buildings.
A good exercise to figure out how this works, is to imagine the problems using the wrong building. E.g. Using a hotel as a boarding school, using a kibbutz as a fishing resort (assume you built it on a lake.)
If you look at western Canada today, there are many community halls dotted around the landscape, many not even connected to a village. Sometimes the community hall is the last remnant of a village. Most of these come down to a large room, often with a stage at one end, an industrial (restaurant) style kitchen, minor amounts of storage for tables and chairs (often under the stage) and bathrooms.
A community hall would work well as an assembly area, a place for dances, big meetings, communal meals. It would be awful as an administration centre (no offices) as a school (no classrooms)
A church, as built by some of the larger evangelical congregations would fill a lot of functions: The main worship centre as a meeting hall; many have classrooms, meeting rooms, a moderate office suite.
Resorts/Hotels attack the accomodation problem, usually without individual cooking facilities.
Boarding schools often have 'bathroom/showers down the hall' and would have privacy issues for family groups. But read up on Kibbutz.
Russian apartments often had a single room per family, with communal washing and cooking facilities.
Much would depend on cultural norms. I know from experience that architecture has a huge impact on social conventions. (I've worked in 3 boarding schools)
Do an outline of your story, then flag elements of the story that take place at the community centre. Abstract these, then design your centre to fit. Bear in mind the limits imposed by your planet: The big grass hutch on a tropical island is ill suited to the Canadian prairie. The Iroquois long house, or the buildings of the west coast Haida might work, with the right forests.