Which company workshop formats do you like?

Hey fellow hackers,
if you ever attended a company workshop (especially in the area of clean code, architectures, or best practices for testing or code review), what was the format like?

Can you recall what parts you enjoyed the most and why?

If you would attend another one, what would your preferred format be?

Also if you have some links to workshops I could look at to see how others do it, that would be wonderful.

Thanks,