Laos - places to go

I'm planning on goign to Laos in the Spring next year.. Can anyone suggest any particulary awesome things to do there? I've read in all the travel books about the more obvious ones such as sailing down the Mekong and visiting Luang Prabang and the surrounding area.. But has anyone got some more detailed suggestions? Thankssss

Here are the list of places that I would suggest that you don't miss
Tiger Trail Outdoor Adventures - Elephant Village and Camp
Kuang Si Falls
Mount Phousi
Traditional Arts and Enthnology Centre
Phu Si Hill
Traditional Arts & Ethnology Centre
Golden City Temple (Wat Xieng Thong)
Nava Mekong
Whisky Village
Kopnoi Export Promotion Center
Tad Sae Waterfall
Royal Palace Museum

Gibbon Experience (may be your only chance to live in a tree house in the jungle) near Xuay Zai.
Fast boat down the Mekong from Xuay Zai to Luang Prabang.
Elephant riding/washing/swimming at a remote village outside Luang Prabang.
Tube-riding, swimming, tapezing into the river and raging at Vang Viang. This is a strange one. Thought I'd hate this place but forced to transit and loved it for for 48 hours.
Laid-back Vientianne