Bangkok is a very lively place throughout the year, so the best time to visit really depends on your personal preferences.
Most people tend to prefer to visit Bangkok between November to March as this is considered to be high season due to it being around Christmas and New Year. The only issue with this time of year is that the climate is definitely not as hot as it is for the rest of the year. The temperature around Christmas tends to average around 25°C(77°F) to 30°C (86°F).
Of course the main disadvantage to traveling at this time is that it also means flights and hotels are more expensive. If you need to travel at this time then one solution to help lower costs would be to book as far in advance as possible as you’ll find better deals by doing it this way and also find that the hotels are likely to be booked up if you book much later.
Once you’ve decided on the flights you want, it’s a good idea when booking through an agent to always specify that you’re after the lowest possible fare available as there may be specials which do not fall under certain titles such as "economy" and are therefore missed opportunities. Moreover, you need to remember that not every agent, not even the budget specialists, will be equally competent or motivated to find you the cheapest deal available.
This should also be the rule when buying tickets on the internet as well as some believe that all prices are cheaper online and this just isn’t the case. The fact is that you still have to put the hard work in for finding those deals by comparing prices on flights at different companies. Something else to consider is transfers, how many you’d be willing to do, do you want certain times, places etc. It’s always going to be cheaper when there are more transfers but if you’re not willing to change and extend your 17 hour flight from the UK to Bangkok anymore, then it might not be worth the saving.
On the other hand, as Bob Atkinson, from comparison website travelsupermarket.com, says: "It's very aggravating to be sitting next to someone who got a better deal." So if you want to see how much you can save, it’s definitely worth visiting Travelsupermarket to get the best deals around.