I've been to Bangkok twice within 3 years. Nice place. I like Chinatown, plenty of food to eat. Don't miss Cha Tuk Chak. Nice place to shop and eat too. If you take cab to travel within the city, tell them to use the meter. If they refuse, take another cab. Don't take tuk tuk. They are expensive. same price as cab.

If you wanna go shopping in a mall, go to MBK and Siam Paragon. Food court is at 6th floor MBK. Plenty of good food to eat. Cheap and tasty. It is even cheaper than the hawker food.

Temples tour in the city would be nice if you like history and architecture.
There is a Buddha statue made of solid gold.

Tour outside Bangkok is quite expensive especially the entrance fee tickets. If you're following a tour and all is inclusive then it is OK. I went there on my own. Don't like to follow tour. I planned my own itineraries.

You'll get a cheaper rate if you book thru a travel agent.

Chinatown is my favorite dinner spot. Plenty of good food to eat if you are going out for dinner. Don't go on Monday nite because most of the eating stalls are not opened.

Don't use tuk tuk. Tuk tuk is more expensive than cab.

MBK food court on 6th floor. Most of the foods are good and cheap.
Chinatown at nite. Choose the the sea food with most patrons.