
I love to see other people who play ToT!
To answer your question, I never automate my settlers, engineers, Dwarves, or other equivalent units. The reasons:
- I don't want to forget about them, especially when barbarians or Dragons are in the neighborhood.
- I want to decide which squares they improve, and how.
- I don't want them to do something incredibly stupid, like build a city on the Gate of Hel entrance.
- I've discovered that Dwarves and Engineers can improve Impassible terrain, and if you teleport a Dwarf to the Cloud World, he can improve Cloud city squares (which results in some really weird stuff on the Magic Clouds). Automating these units wouldn't let them do those things.
- I build roads/railroads/ley lines on EVERY square.