"play the gambit" = how I say it, for starting a clever tactical opening move at the start of a situation. You hear it used in political situations, in ever changing politically changing UK. I Also know it refers to the first move of a chess game sacrificing one pawn to gain an advantage. Almost the first thing I was taught when I played chess for a while as a teenager.
"Run the gamut" = I use extremely rarely to refer to somebody "running the show" or "running the whole show" which are are informal colloquially ways of saying the same thing, I think.
"Running the Gauntlet" or "To run the Gauntlet" I use and associate with a risky situation, with a small degree of overlap with "to play a gambit" if the gambit is considered to be risky or riskier than just a 50/50 chance of success or it is obvious that if the gambit backfires the player losses everything or a lot, in terms of things like reputation, wealth, integrity, honour, job loss.
Other than that I use "run the gauntlet" for competitive games and sports or dangerous combats.
Plus there is the colloquialism to "throw down the gauntlet" presumably from medieval joisting times.