I just have to put in the biggest pro for sticking to trains - the feeling. Nothing gives you a more free feeling of independant travelling than sitting on a train, seeing the landscape go by and knowing you'll be in Paris, Rome or some other place by next day. Getting to sleep on a train also adds to that, knowing you will wake up in another country.
The traintraveller also gets the whole social aspect of backpacking that someone travelling by plane doesn't. It is much easier to connect with someone in the same coupé on a train, than with someone sitting next to you on the plane. Of course you might get stuck with some freaky person on a train too - but that'll only lead to a funny tale to tell you friends later.
The third reason to take trains, is the fact that they bring you to places airplanes never go to. If you see some nice-looking place on the countryside, where to train stops, you can just get off and explore. That will be a bit hard if you're on a plane. Furthermore, some places are wholly unreachable by air - and if you focus too much on getting to places fast and cheap, you'll probably miss those places.
With all of this, I'm not saying airplane travel is something bad for a backpacker - not at all. I love the fact that an airplane can take you anywhere around the globe in just a couple of hours. But if you really want to experience that backpacker feeling of railing round Europe - you should do it totally by train. Just for the hell of it.
Bus travel is out for you, because it takes so long.
For example, from Berlin to London: Car 11hrs (if you can switch drivers and have no delays), plane 4-5 hrs including transit to and from the airports, train 12 to 16 hrs, bus 18 hrs.
Bus is usually only worth it if you got lots of time and very little money.
With a rail pass, the train cannot be beaten - cheap, relatively fast and comfortable. You can get up, walk around and if you are lucky you have several seats to yourself, giving you enough space to stretch out and nap. Booking a couchette or sleeper is easy and very good value. (Just think of what you pay for a sleeper seat in first class on a plane.)
One more tip: Since the Eurostar train is not included in a Eurail pass, compare with prices for ferries if you need to cross the Channel. There are quite a lot of ferries that are easy to reach by train.
[ Edit: Edited on Apr 12, 2007, at 1:33 PM by t_maia ]
Thankyou to everyone!!!
I think we're gonna go with the trains - I'm working on a plan that will mean we will get around to all the places we want to go without having to spend more than 4 1/2hrs on the train at a time. The idea of being able to get up and stretch my legs was the clincher and definitely helped to make up my mind. It'll be worth the extra money for that alone. Arriving in the middle of the city will also be a big bonus. The couple of times that we'll have to spend longer on the train, I'm going to try and book a sleeper overnight.
Thanks to the people who suggested the cheap flights - in our case most of the cities we want to visit are in adjoining countries but we will need to get from Dublin to Paris and you've helped me find a cheaper flight than I might have otherwise. And I'm sure you've helped a lot of other people out there too!!