I always try to see if the train works vs a plane due to security and hassle of the airport, and getting there and back. Consider very early, very late, or even night trains (sleeper and non-sleeper). You can save time traveling through the night if it doesn't bother you. If I were traveling alone and didn't need to worry about departure and arrival time due to kids and family, I would. I can sleep in a seat off and on.
Check omio.com for tickets. It compares trains to buses and planes, and also driving. Not a bad site, but the best for trains is Deutsche Bahn (bahn.de/en), at least for times and connections (prices not always available). If you book early enough, you can get quite good deals, especially for the early/very late trains as discussed above.
Even if scenery isn't spectacular, it's just so much more laid back, and you have a lot more freedom.
Enjoy.