The weather is always nice in Sri Lanka cos it's close to equator. One of the best things to do is hike or bike through the tea country in the south-central region. I also enjoyed rafting just outside of Colombo (on the river they filmed Bridge on the River Kwai). Mellow beachfront fringe the entire coast--and you can get to the Seychelles from there easily, if you like to dive. The southern city of Galle is a spectacular, old-world walled city, while Kandy has got amazing temples.