The soaring limestone cliffs, white sandy bays and colorful shacks found on Thailand's islands make the country one of the world's quintessential paradise destinations. But while few places are better for a sun-drenched vacation, there's so much more to do beyond kicking back with a cocktail. Head north to Chiang Mai for the very best in fresh Thai cooking and long bike rides through the surrounding hills and paddy fields; trek the forests and mountains near Chiang Rai and explore Ayutthaya's ancient temples. Bangkok, meanwhile, is the ultimate Southeast Asian metropolis, a lightning-paced city filled with scintillating rooftop bars and delicious street-food spots.