I run a lot of con games that might qualify: 3 to 5 slots, intended to provide a complete experience for those that play multiple or all sessions, as well as singular session fun for the one timers.
I tend to switch between "story" con campaigns and "episodic" con campaigns, depending on my preferences.
What i find is that folks really like short campaigns compressed into a weekend. They get the "epicnesss" of a campaign without spending 60 sessions.
As to characters, there are 2 possibilities: in the story campaigns, death isn't really on the table unless a player is in to that. In more episodic games, I have a giant pile of pregens ready to go.
I hope that helped but if you need more detail I am happy to answer questions. I have been doing this for 10 years or so at this poignant have learned a lot.