I can honestly say I have never wanted to teach a group younger than juniors or seniors in high school. I do lack patience with the emotional drama of preteens, and generally cannot take the noise of large groups of young children. I am currently homeschooling my son, which is challenging to manage my short attention span and his at the same time. Luckily, teaching him one on one is not too bad, and since we have similar limitations it seems to work well.
The idea of having 20 or 30 six year olds in one room with me all day, well, that is my idea of a surefire way to end up insane in less than a week! Teaching college works well for me, I don't think anything younger would work. I cannot imagine co-teaching. I don't know how I would manage that. I don't work from lesson plans because I have a nearly photographic memory. I am told by my students that they like the quirky way I pull facts from diverse sources to ilustrate connections between historical texts and modern day events. I encourage class participation, and often a question from a student will lead us through a somewhat crazy sounding path that leads us back to the text they are reading. I have had to learn to edit the amount of information I throw at them, and remind myself to check and make sure they are following my train of thought or I get a lot of really weird looks, but no one sleeps in my class for fear of missing something! 