Routes through the region are as varied as the ragtag bunch that travels them. With the many convenient air connections, you can choose your destinations and connect them as you like, but here are a few suggestions to get you started.
Touring Indochina -- Clockwise or counterclockwise routes starting in Bangkok and including northern Thailand, Laos, Vietnam, and Cambodia are popular and avoid boring backtracking. Connecting northern Thailand with Laos by boat is appealing, and flying from Vientiane, the Lao capital, to Hanoi or Ho Chi Minh City is a better choice than the rough overland route (which also leaves you in the middle of the north-south route, whereas a flight will get you to a terminus). After a sweep down the coast of Vietnam, connect with Cambodia overland (or by boat from the Mekong Delta) and continue on to Angkor Wat by bus, boat, or plane. There is frequent air service between Angkor Wat and Bangkok.
This itinerary can take anywhere from a few weeks to 6 months, depending on your inclinations. Highlights include the historic temple towns of Thailand, hill-tribe treks throughout the region, sleepy Luang Prabang, busy Hanoi and Ho Chi Minh City (Saigon), all of the stops along coastal Vietnam (historical and recreational), and, of course, Angkor Wat. After a trip like this, you'll have earned your time on the beaches of Thailand, Malaysia, or Bali.
Heading Down the Malay Peninsula -- Starting in Bangkok and heading south, you can connect the major resort destinations of southern Thailand with a tour down the length of Malaysia to Singapore and end up in Bali.
You can do this trip in a fly-by-night week or stretch it out over a few months. Highlights include pristine beaches (maybe even The Beach) in Thailand; great food, affordable cosmopolitan comforts, and cultural stops in Malaysia; "shop-till-you-drop" spending in Singapore; and the tranquil beaches of Bali.
Basing Yourself in a Hub -- From Bangkok, Singapore, or other major urban centers, travelers can make short forays into the countryside or to the resort of their choice from a comfortable, familiar base in a big city with all the comforts of home. Many visitors aim for the cultural and historic sights recommended by UNESCO -- places such as Luang Prabang (Laos); Hoi An, Hue, and Halong Bay (Vietnam); Sukhothai and Ayuthaya (Thailand); and the temples of Angkor Wat (Cambodia) -- all reachable via larger cities. Or start in a comfy hub and connect with local outfitters for short adventure trips before coming back to hot showers and room service.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.