Alex at 2011-12-22 19:13:40:
Someone else old me this so I can't take credit for this bit of wisdom, but try thinking of TV as a narrative that explores what your characters do on a daily or weekly basis, whereas a feature film explores what your characters do in the most extreme/extraordinary moments of their lives.
Chris Stein at 2011-12-22 20:21:42:
If the idea is more "event driven" it's a movie. The whole thing about a movie is that something happens to your protag that forces them to take action. Most films adhear to this. If the idea is more "slice of life / character driven" or "profession driven", chances are it is a TV show. TV shows rotate more about how your characters will deal and continue to live as stuff is thrown at them. Or, the main emphasis is about their profession like being an ER doctor, a detective or a medium. Is it about how an event affects protag or is it how the protags continue to deal with whatever is thrown at them.
Debbie Moon at 2011-12-23 04:52:36:
I'm dealing with an idea at the moment that could go either way. Sometimes your premise could be the worst/best day of the protagonist's life, and it could also be their ordinary life. For example, the extraordinary opportunity the characters receive in the movie Stargate then went on to become their everyday job/life in Stargate SG:1.
pliny the elder at 2011-12-23 22:31:46:
The complication is the serial TV show, like Galactica, Heroes or Lost. In some senses you can treat such a show as a big movie spread over the course of a season, where instead of telling just one story, many narratives are interwoven. There's a lot to be said for giving yourself enough room to tell a big story. People like Darabont and Sorkin keep returning to TV precisely because of the expanded options for character it affords to writers of that caliber.