I think between four and six people makes the right sized party. For me it is difficult being in large groups, so large parties are not my thing. Plus a small group type setting allows for more intimate conversations. There is an ability for the entire group to be involved in what is going on instead of members of the party breaking off into their own group.
Also if one enjoys board games as I do, six seems to be just the right amount to ensure all people can be included in playing a board game.
Adairmoon 