IamMANWell then sounds like you already got an idea there. If you don't want to listen to anyone who has already been in Europe, seems silly to ask.
Night trains since you want to see 100 places in 10 days. You can sleep on the train and wake up somewhere new. Won't be easy on your wallet but hey, that is what you want to do.
I would also recommend what the others previously have mentioned.
However you could do Oslo, Copenhagen, Hamburg and Berlin. I would definitely not recommend more than 4 places. When one travels to a ton of places in a short amount of time, one can barely say that he was even there. It is equivalent to being in the airport and saying "Yea I have been in Dubai... well only the airport, but it was really cool."
Well for the record I did ask what the best mode of transportation would be not for tips on planning my trip.
And since everyone is so pushy on the travel advice. The trip isn't 10 days. Im spending 7-10 days in Norway. I've already seen all I want to see in Oslo and won't be spending any time there other than maybe a night waiting to fly out.
I will also likely be getting to barcelona around the 29th or 20th. So I have a block of 10-12 days for anywhere I want to in Europe and i'm going to bounce around quite a bit.
One person mentioned the size comparison to the USA. I bounce around the USA all the time road tripping from north to south East to West.
Spending 2 or 3 days in a city is plenty for me. I moved around pretty quickly and cover a lot each day. That's nothing like the airport terminal.
Once again, I don't really give a fuck that nobody likes the way I travel. I don't see why that's so hard to understand. I understand I asked for advice and now I'm being a dick, but people aren't listening.
I'm doing some snowboarding and hiking in Norway, I'm doing chilling out and whatever in barcelona I'm probably hiking a mountain in Morocco. I'm totally fine with doing some other places by the city in a short amount of time.
If I really was tying to understand a whole country, the culture, see it all experience it all I'd go for a few weeks absolutely minimum. Like I said, I don't even care about that. Europe was a trip I wasn't even going to do for a few years. I just impulse bought a cheap flight to get back to Norway.
So if I ever mention that' I've been to france after this trip feel free to find me and call me out for only having been to paris, and it only having been for 3 days. You can tell me how I didn't see enough of the country, didn't spend enough time there, and that I'm a horrible person or whatever.
I'm not very worried.