Thanks for all the replies . I will get back with something more substantive to say in response later, but for now I just want to bump the thread.
Actually, I would like to remark on the similarity of the responses so far. It seems that most of you prefer to be non-authoritarian and humorous (which I suppose I could have guessed myself), but I would still like to know how it 'feels' to you when you do it. Do you have to have an organized plan to be comfortable lecturing? Do you feel insecure in front of the students? Do you prefer lecturing to pure discussion (I'm thinking of the formats where you're in a circle and all that goes on is group discussion, which may or may not correspond to your plan for the lesson)? How do you deal with silences during discussion, if you have any?
Anyway, I appreciate the responses so far, thanks.