Optional
Deity

I usually want Republic as my government, but sometimes I can't get there quick. In my most recent game, as the Mayans on Pangaea, Demigod, I managed the Philosophy slingshot - not bad for a civ that doesn't start with Alphabet.
A couple of civs were up Polytheism, so I could trade for that, and grab Monarchy as my freeby. I wanted Republic, but switching to Monarchy was very attractive - there was a forest game in my core and several floodplains; my growth would benefit from removal of the Despotism penalty right there.
I couldn't resist the temptation and switched. I triggered my Golden Age with a Javelin Thrower a touch later, which helped me build the Hanging Gardens and lots of other stuff.
I didn't really use the Monarchy government as a war government; my wars were mainly phony wars. Mostly I built culture, including Copernicus, Sistine's, Bach's and Newton's.
Then I felt my research would get another boost if I were to switch again. Six turns of Anarchy later Republic shaved off about two turns of research for every tech.
Would you have switched twice you think?