Laos is without doubt one of my very favourite countries - in fact I could even go so far as to say my favourite country. The people are the friendliest, the vibe is so chilled it's hard to believe, it costs almost nothing to travel there (At one point I was paying US$1 a night for my own bamboo hut set in a picturesque location on the banks of a clear river surrounded by forest and high limestone cliffs) and there was a good combination of backpacker hangouts and opportunities to get off the beaten track too.
They also had South-East Asian New Year while I was there, the end of the dry season and the coming of the rainy season - usually about mid-April. It was 3 days of madness, with water fights and flour bombs being hurtled all around the two locations I was in over the 3 days - the small village of Muong Ngoi and the "city" (well, its called a city but it sure don't feel like one) of Luang Prabang.
But the real highlight for me was getting off the Lonely Planet Ant-Trail of Luang Prabang, Vang Vien and Vientiane - some smaller villages further north of Luang Prabang were some of the most super-chilled places I've been, with good walks, clean rivers to swim in, caves to discover and of course a few leeches to avoid! Watch out for those little buggers.