Should I book a round-trip or two one-way tickets?

Usually, a round-trip ticket is cheaper, but check budget airlines for one-way options if you are planning to travel around Southeast Asia.

Is it cheaper to book directly with the airline?

Yes. If there is a flight cancellation or change, dealing directly with the airline is much easier than going through a third-party booking site.

How to book cheap flights to Bangkok

To get the cheapest fare to Bangkok, book 3 to 5 months in advance and avoid flying during the peak season from November to February. Use Google Flights to track prices and set alerts for your specific travel dates to capture price drops before they spike.

Use incognito mode and broad search tools. Open Google Flights and set your departure airport. Enter 'BKK' as the destination. Select 'Flexible dates' to see a calendar view of the cheapest departure days.
Set up price tracking. Once you have your preferred dates, toggle the 'Track prices' switch. You will receive an email whenever the price for that route drops significantly.
Check regional airports. Don't just search for flights to BKK. Check flights into DMK (Don Mueang), which often hosts low-cost carriers like AirAsia, potentially saving you $100+.
Book during the off-season. Aim for May, June, or September. Flights are consistently 20-30% cheaper during these monsoon months compared to the December holidays.

Should I book a round-trip or two one-way tickets?: Usually, a round-trip ticket is cheaper, but check budget airlines for one-way options if you are planning to travel around Southeast Asia.
Is it cheaper to book directly with the airline?: Yes. If there is a flight cancellation or change, dealing directly with the airline is much easier than going through a third-party booking site.