Khao Yai, Thailand
Just take a couple of hours North of Bangkok, Khao Yai is known first and foremost for its Unesco-listed National Park, the first nature reserve of its kind in Thailand (was established in 1962). The park has an extensive network of trails, with many waterfalls and wide variety of wildlife to spot, from elephants to gibbons. The area is a popular weekend escape for Bangkok's residents, and you'll find everything from one of Thailand's few wineries to a contemporary art museum and sculpture garden. Khao Yai is also home to numerous Vegas-style themed resorts, including a Hobbit-style Shire and a recreated Italian village.
Luang Prabang, Laos
A town filled with graceful temples and orange-clad monks, the picturesque Luang Prabang asks to be enjoyed at a nice slow pace. Although it's now a well-worn stop along the backpacker trail, this highly cultured town has a lot to recommend it. The atmospheric streets are Unesco protected meaning that those misty views over the Mekong river are still the same as they were centuries ago. Moreover, don't' forget to visit the morning market, or Wat Xieng Thong, the town's most impressive temple.
Koh Kong, Cambodia
The largely undeveloped area of Koh Kong is something of a paradise for nature lovers. The Cardamom mountain range found here is home to some of the world's rarest species, like the Asian elephant and the wonderfully named clouded leopard. Consider organising a guided day-long trek to explore the virgin forests and impressive waterfalls hidden in the hills, though spotting a clouded leopard is sadly unlikely. For some beach time, hop on a boat to Koh Kong island, home to several pristine beaches with good snorkeling. Alternatively, explore the mangrove forests outside Koh Kong town at the Peam Krasaop Wildlife Sanctuary. If you're lucky, you might see a pod of Irrawaddy dolphins.
Lak Lake, Vietnam
Located 150 km from North of Da Lat in the Central Highlands, Lak Lake was once a favorite beauty spot of Emperor Bao Dai (1926 to 1945), who built a palace overlooking the water. Nowadays it's a popular spot with tourists, many of whom come to take part in "traditional" Vietnamese excursions. Nonetheless, visitors who manage to dodge these activities will be rewarded with lazy days on the lake – you can hire a longboat operator to take you out on the water and the chance to explore the Mnong villages of rattan and stilt homes along the lake. To head slightly further afield hire a bike and head into the countryside where there are coffee and rubber plantations to explore.