Try to avoid spending your first 3 days in Bangkok. If you start here after your intercontinental flight, there is a big chance by the third day you are so overwhelmed by the heat, the noise and the cars of the city, that you just will want to get out! I know this is a convenient way of starting your holiday in Thailand, from the plane into the big city. You are there anyway. But better spend the first 3-4 days on the beach. Bangkok is a hectic crazy city. It is hot, humid, busy, never sleeps, noisy, smelly... Keep this experience for the final days of your stay as you will be more used to he temperatures and the humidity and you will have had some good nights sleep.