Should I book a package deal including a hotel?

Only if you have a specific resort in mind. Often, booking flights and hotels separately allows for more flexibility and lower costs.

Is it cheaper to fly into Cozumel and take the ferry?

Rarely. By the time you pay for the ferry and ground transport to Cancún, you usually end up spending more than just flying directly into CUN.

Finding Cheap Flights to Cancún from the US

Use Google Flights to set price alerts at least three months before your trip and target mid-week departures, specifically Tuesdays and Wednesdays. Avoid flying during Mexican Spring Break (mid-March) and the weeks surrounding Christmas to keep your airfare costs low.

Set a Google Flights tracker. Input your departure city and CUN as the destination. Toggle the 'Track prices' switch. This will email you daily updates when prices drop or rise significantly.
Use the calendar view. Open the calendar in Google Flights to see the cheapest dates highlighted in green. A shift of just 24 hours can often save you $100 or more.
Check budget carriers. Include airlines like Southwest (not on Google Flights, check their site directly) and Spirit or Frontier. Be careful with 'hidden' costs; a $100 fare on a budget airline can become $250 once you add a carry-on bag and seat selection.
Book at the 6-to-8-week window. For international flights to Mexico, the 'sweet spot' for booking is usually 6 to 8 weeks before departure. Don't wait until the last 14 days, as prices spike.

Should I book a package deal including a hotel?: Only if you have a specific resort in mind. Often, booking flights and hotels separately allows for more flexibility and lower costs.
Is it cheaper to fly into Cozumel and take the ferry?: Rarely. By the time you pay for the ferry and ground transport to Cancún, you usually end up spending more than just flying directly into CUN.