I have a game group that is six players plus me, the DM. Because of schedules and geography, I rarely get all six in a single game. For the last story arc, we agreed that every character had other important things they could be doing, so there wasn’t a need to explain anyone’s absence from a particular session. We would do a recap at the beginning of each session anyway, so people were mostly able to follow along. It worked, though it wasn’t a great solution.
The players are on the verge of paragon tier, and when the current storyline wraps up, the characters will be able to pursue whatever objectives they wish. I want to make sure that there is more continuity from one session to the next, so I came up with an idea that sounds great in my head, which means my players are going to hate it.
First I would place the players into three pairs. Mahelo and Rolen, the sorcerer and the ranger, would be one; they are played by two roommates. Zeelatar and Slammer, the runepriest and the paladin, would be a second; they are played by a husband and wife. Brie and Riot, the warlord and the cleric, would be the third; no relation between the players, but the two characters are closely tied together in backstory and actual events in the campaign.
Within these pairs, the players would have to come up with a single goal that they want their characters to accomplish and that would naturally lead them to work together. The goals could be as simple or elaborate as they like, and they would be free to invent whatever story elements they like. They should be the sort of goals that would reasonably take an entire tier to accomplish.
Then I would mix them up into different pairs. I’m thinking Mahelo-Zeelatar, Slammer-Riot, Rolen-Brie. We would repeat the process, coming up with entirely different goals. At the end, every character will have two goals they want to accomplish in the next ten levels, and two buddies who will help them do it. That way we can always be advancing the story no matter who is or isn’t at the table that day, and nobody will ever miss out on events that would have been pertinent to their character’s objectives.
Like I said, it sounds great in my head.