Bangkok has the longest city name in the world - "City of Angels, Great City of Immortals, Magnificent City of the Nine Gems, Seat of the King, City of Royal Palaces, Home of the Gods Incarnate, Built by Visvakarma at Indra's Behest" - kids will have fun remembering this when you visit.
Getting around - The best way to get around the old city area, which includes the Grand palace, Wat Pho, is to take the river ferry, Chayo Phraya Express boat. In the downtown area, the Skytrain (BTS) and subway (MTR) is modern, speedy and efficient. Traffic on Bangkok city streets is highly congested and full of exhaust fumes. It's fun to take a tuk tuk for short hops (negociate price in advance), but for longer rides, take a taxi.
Fun food
Any time of day in Bangkok, kids will want to try different fresh fruit drinks - orange, lime, lemon grass (something different), banana, mango, watermelon, strawberry milkshakes, coconut ice cream and popsicles.
Also it's fun for kids to watch street vendors grilling bananas, frying things in big woks, assembling hot bowls of noodles, slicing fresh fruits into all sorts of cut shapes.
Shopping -
There's no end of Thai souvenir shopping - painted umbrellas, fold up bamboo hats, wooden elephants and tigers, silk coin purses, scarves, and clothing, lots of different jewelry, kites, miniature tuk tuks.
Here's our own Travel for Kids hand-picked list of family hotels, all styles and price ranges, convenient to fun things to do with kids in Bangkok: