I've been playing with the idea of writing a story from the point of view of an entire town for quite a while. I want to have one central character who is well-known and the basis of the story, but the story will never actually be from the point of view of that character. I want to have most of the story revolve around the town's speculation of and reaction to this character and also have side-plots for the other characters. (I realize after having read the first thirty pages of The Casual Vacancy by JK Rowling that it is very similar, but I came up with this idea long before I read it. It's different enough, I think.) Anyway, my main question is: how many characters is too many? I want to have enough characters to create complicated, overlapping story lines as well as to emphasize the fact that I'm writing about the whole town and not just a select few, but I don't want to confuse the reader.
Some books contain charts and graphs of people and names to help us keep track. Some books only have a few characters. Sadly, the "whatever fits" answer seems to be the one you'll end up getting. Now, you'll have side plots. Each side plot may have 2-8 characters (generally), and these may overlap a bit with other side plots. So if you have say five or six stories that are side plots, you'd end up with between 10-48 characters, including the central one. Taking into account some overlap and variability, a realistic "big town" of characters would probably be about thirty. That's what I'd aim for if I were writing a story revolving around a town's reaction to one person.
My suggestion is to start writing. You will weed out unnecessary characters as you go, and then further pare down on editing. Don't get so hung up in the planning that you never get started actually writing it.
As few as necessary to relay the story. Selecting POVs with as little overlap as possible, yet travel through similar social circles seems like the way to go: The owner of a local hardware store A waitress at a small diner The mayor A school bus driver The main character's spouse or daughter or son A Neighbor or Landlord A Coworker A pastor or priest See some things could double up or make the connection. The spouse could work in the village office with the mayor. A coworker could be on the same bowling team as the character being observed or the central focus, many of them may attend the same church in town, etc. The bus driver could visit the diner, and pick up the character's kids, etc. But if you get too many, you diluting the story. Each should have a unique perspective and something signifcant to add. That's my two cents. Good luck as you move forward.
A strong story, with a simple plot could be told from multiple viewpoints. It would be interesting if the viewpoints differ, because the characters certainly would! There's a film about a female helicopter pilot who is being considered for the Medal of Honor (Meg Ryan?). Told with different viewpoints from participants, all with an axe to grind. I bet a google search would find lots of novels and movies to pique ones interest. Does Canterbury Tales qualify?
I've actually been brainstorming a similar type of story. I would say stick with those character who actually have something to do with the central plot. And sometimes two people (such as a married couple) may have the same plot thread, so that can make that kind of thing easier to manage. Start with a handful and just add them as needed. Too many gets confusing for author and reader both.
Use as few as it takes. But there are exceptions to every rule, it seems. Read Edgar Lee Masters, Spoon River Anthology. He did poetically something like you are proposing. I wouldn't say he did a great job of tying it all together, but the overlaps let you tie a lot together and imagine much of the picture where there are gaps. It's a very good study in how different people see the same things differently. From wikipedia: The collection includes two hundred and twelve separate characters, all providing two-hundred forty-four accounts of their lives and losses.
As many as you need. 1984's whole cast of characters are basically Winston Smith, Julia, O'Brien, possibly that Thought Police dude in disguise as an antique shop owner and... that's about it. Three peeps. On the other end of the spectrum, George R.R Martin and J.R Tolkien have literally hundreds of characters. It got to the point where I forgot pretty much every single character except the main ones like Tyrion, Arya, Bran etc.
maybe start writing it from one POV, then when you need another one start that one. This will keep it down to exactly what you need