Fjords to Southern Tip of Norway

I will be traveling from Flam to Kristiansand and am wondering if anyone has any suggestions about which route to go. I am trying not to get into Kristiansand too late on the second day as relatives will be picking us up. There are a couple different options:

1. Take the train to Oslo and spend the night-train to Kristiansand next day.
2. Take the train to Drammen and spend the night there- train to Kristiansand the next day (this would save a bit of time and hotels are less expensive.
3. Take the express boat to Bergen- spend the night in Bergen. The next day take either the bus or combination of boat and train to Kristiansand.
4. Take the express boat to Bergen and then overnight train to Oslo. In the morning take the train to Kristiansand.