I have to say, I LOVE Finland. Love, love, love it. But truly, all of those countries sound incredible! Eastern Europe and the Nordic nations are absolutely fantastic, and I'd say that you should try to plan stops in as many of those countries as possible. Luxembourg is also said to be gorgeous. :)
I'd really suggest checking these places out in Finland, if you do backpack there:
-Helsinki is the most metropolitan city in Finland, but it still might be worth your while to check it out! Besides that, it's surrounded by beautiful countryside. Helsinki has fantastic restaurants, a zoo situated on an island close to the harbor, which is the only place in southern Finland where you'll find polar bears, contrary to rumors xD, excellent shopping centers (especially if you want to buy textiles or silverware! Iittala designs are known around the world, as is Marimekko fashion), and a great music scene (Finns love music!).
-Savonlinna, in eastern Finland, is absolutely stunning. The lakes are clear and beautiful, and a traditional sauna in Savonlinna is the epitome of the Finnish experience!
-It may also be worth your while to take a ferry out to the Aland islands, which is a Swedish-speaking province of Finland. Aland is adorable to me- all of the homes are painted bright, cheerful colors, and the harbor is gorgeous!
I hope you have an amazing experience, wherever you go! I'd also recommend checking out Estonia- the language and land is a lot like that of Finland's (except I think Estonia is even more beautiful!) and the people are polite and friendly.
I have to add that people in the Nordic countries (Finland, Iceland, Denmark, Sweden, Norway) speak near-perfect English, so they'd be great places for English-speakers to travel. :)
Finnish-American with a passion for different countries and cultures. :)