I'm running an Amber campaign with 6 players and it seems like perhaps that's too many.

1. Some of the players get impatient with their down-time, and they have a lot of it since there are so many players to juggle.

2. My group tends to be less competitive and more cooperative, so you get this pack of six Amberites running around in a small group. It's tricky to come up with a challenge worthy of standing up to six Amberites at a time.

So ... what is the "optimal" group size for an Amber campaign, and what tricks do you use as a GM when running larger groups?

Well, one thing would be to break them into smaller clumps but try to ensure that they're never alone. That way, at least, players can do in-character discussion and the like while the GM's attention is elsewhere and it's not really "down-time."

Another thought is that parents (in Amber as well as in life) can be great at pressuring PCs into pursuing goals that don't altogether jibe (or in fact flat-out conflict) with group interests. I've recently been re-reading the Merlin books and its amazing how much mileage Zelazny gets out of having parents lean on their offspring to do things that the kids do won't want to do (e.g., Luke and Merlin, etc, etc, etc). Even if your group tends to prefer "co-operative" play, this seems to me an entirely kosher challenge to throw at them and resolving the tension between personal, parental, and group goals should only be grist for the mill of good roleplayers.

Something else that emerges from the books is the non-"real power" parent can and should just be as major a concern in the character's life as the other parent. They often seem to get neglected in play.

I find that four players is great in somewhat cooperative games, while 6-8 is great for cut-throat Amber.

With six players who like to cooperate, I@d be tempted to force them to split into two or three groups. Two would be optimal from the down time point of view, but three might make it easier to challenge the them.

The easiest way to do this is to present a challenge with multiple threats operating simultaneously. If the enemy (or whatever else threatens the group) is also split into team then this can be pretty easy. Otherwise any variation on the evil mastermind forcing the group to choose between friends, family, loved ones, etc works well. The players think they can circumvent the dilemma by splitting up, but you have the last laugh as each group is easier to challenge further.

My group has 7-9 players.  Amber is best when its big, because then you form cliques and cabals.

Also, as already said here, you cannot undervalue the importance of parents for helping children turn against each other.

RPGPundit

Good advice so far.
 
Another way to split them up is to give them armies to lead. Players can become very sentimental about protecting their armies, especialy when they've got plans for using them in the near future.

Quote from: Malleus Arianorum;249781Good advice so far.
 
Another way to split them up is to give them armies to lead. Players can become very sentimental about protecting their armies, especialy when they've got plans for using them in the near future.

I know! Don't you love it when your players think big!?