I belong to two quilt guilds that are as different as night and day. One is large (135!) and one is small (35 now). Both have cliques and some people are nicer than others in both groups.
It is important to decide what your objective is in joining a guild: make friends, learn things, be inspired or whatever. In both guilds, I have found that it has been hard to get acquainted.
I've also found that volunteering for a position is a good way to get to involved. In the larger quilt guild, I stood up (shaking in my boots) and asked if anyone would like to join my "small group" (only 5 or 6, we meet in each other's homes to sew monthly). A few people volunteered and that has been the BEST experience for me.