My first interrail

Perfecto. Gracias!

Y ahora en ingles! 

I would recommend Dresden, Leipzig and Brno as quieter cities with far fewer tourists. Also ‘Saxon Switzerland’ near the DE-CZ border and Zakopane in Poland both look beautiful, though I’ve never been.

After Budapest, you have a choice: keep going east to Romania (Brasov, Cluj-Napoca?), or turn south to the Balkans. Both good, maybe very hot in summer? Or go back north to Poland and the Baltic States. Summer is a great time there.

Taking into account your recommendations, my trip would be like this:

1. San Sebastian- Berlin.
2. Berlin - Dresde.
3. Dresde Krakovia.
4. Krakovia- Budapest. 
5. Budapest - Eslovenia?

I think after Budapest I would like to visit Eslovenia and after that I don't know. I think that the Balkans is what attracts me more but I will be very far. 

A good choice. I liked Ljubljana and Lake Bled/ Triglav National Park.

From Ljubljana, the train journey to Zagreb is beautiful, and I think Zagreb is a more interesting city.

Many people then go down to Split by sleeper train. That’s where the railway ends, and you need a bus or high-speed boat to reach Dubrovnik. Beautiful city, but very very busy.

From Dubrovnik, bus to Mostar - another great city with really interesting mix of cultures. Then train to Sarajevo.

Or bus to Montenegro, then you can take the Bar-Belgrade railway, which is supposed to be beautiful.

Wow. Thank you very much. I will take into account all your recommendations. THANKS!!!!!

I think that my problem is that I only have 7 days to travel.

The trick is to avoid using the pass on days when you can buy cheap tickets. You can get Berlin-Dresden for €20 if you buy far in advance.

Train and bus travel is very cheap in the Balkans:

Bar-Belgrade €24
Mostar-Sarajevo €7

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You also have sleeper from Vienna to Paris for the way home (runs Tuesday, Thursday, Sunday). So for example you can travel from Croatia or Hungary to Vienna during the day, then board the sleeper to Paris. Just one travel day.

Or travel to Paris during the day, and board the Paris-Hendaye sleeper.

Perfect! Thank you!