Question : How long do most people visit Montpellier?
Answer : Of course you're not most people, but if you were, you'd stay roughly 15 days.
Question : Can you cut down on flight costs by changing the day of the week you travel to Montpellier?
Answer : Friday is your cheapest day to fly in March. Having flexibility in your travel plans means you can save more, so be sure to plan ahead when possible.