A mini-series could be an option as well.
The biggest reason I feel a long-running tv show won't work is because of the reasons I stated earlier. Serialized tv doesn't seem to work anymore. With some exceptions ofcourse, most shows fail after one or two seasons. I'd hate to get my hopes up with a new show, only to have it cancelled after a while. I do see how tv-movies couldn't work well either though.
So perhaps, a mini-series of 6 episodes, telling a story from beginning to end, might be a good option.