Thais are passionate about food, and love discovering out-of-the-way shops that prepare unexpectedly tasty dishes. Nowhere is this truer—or more feasible—than in Bangkok. The city's residents always seem to be eating, so the tastes and smells of Thailand's cuisine surround you day and night. That said, Bangkok's restaurant scene is also a minefield, largely because the relationship between price and quality at times seems almost inverse. For every hole-in-the-wall gem serving the best sticky rice, larb (meat salad), and som tam (the hot-and-sour green-papaya salad that is the ultimate Thai staple) you've ever had, there's an overpriced hotel restaurant serving touristy, toned-down fare. In general, the best Thai food in the city is generally at the most bare-bones, even run-down restaurants, not at famous, upscale places.
If you want a break from Thai food, plenty of other world cuisines are well represented. Best among them is Chinese, although there's decent Japanese and Korean food as well. The city's ubiquitous noodle shops have their roots in China, as do roast-meat purveyors, whose historical inspiration was Cantonese. Western fare tends to suffer from the distance, although in the past few years, there has been an incredible increase in the number of upscale and trendy western eateries, some of them quite excellent.
As with anything in Bangkok, travel time is a major consideration when choosing a restaurant. If you're short on time or patience, choose a place that's an easy walk from a Skytrain or subway station. Note that the easiest way to reach a riverside eatery is often an express boat on the Chaoe Phraya River.