Charlie Stross recently reported on
a tropical resort in Germany that should give you some ideas for a city in a bottle. I'll also echo the observations that if you're in a tight ecosystem there will be strict rules on individual behavior. Not necessarily a dictatorship - you could easily have a democracy. But you can't let people do their own thing if that will imperil society as a whole.
For low tech versions, I'd study isolated island cultures. Which I don't really know much about so I can't help you much there.
Note if you have a small population without advanced genetic technology, you might have a lot of strict mating taboos and mandates to insure genetic diversity and health and/or oddball genetic conditions becoming common.