WordNet sense 1 (effusively sociable):

clubbish

WordNet sense 2 (inclined to or conducive to companionship with others):

sociable

WordNet sense 3 (befitting or characteristic of those who incline to social exclusiveness and who rebuff the advances of people considered inferior):

clannish, cliquish, snobbish, snobby

WordNet sense 4 (confined to particular persons or groups or providing privacy):

private