2 weeks, August
Things to do:
-Eat doner kebab at Mustafas in Berlin. No matter the line I promise you are in for a treat. 
-Go wander the gorgeous city of Heidelberg. 
-Night life in Berlin is simply awesome. It is wild, carries on all night, and full of bizarre and cool people. If you can, try to find a local to go with. The bouncers will be kinder if you speak German/or with someone who does. 

-Frankfurt is a common layover destination and many do not have positive things to say about the city. I had my own personal tour guide, a wonderful women who I had met in Laos, who showed me why she loved the city. So next time, instead of avoiding a long layover, embrace the extra time and make an exploration of it. 
     -Ride around river on rented bicycles
     -Visit the many museums in the area
     -Try the local apple wine     
-The museums in Berlin are cheap and fun so check them out. My favorite was the DDR museum. 
-People are very friend in Germany so ask their advice. See what the locals suggest, they usually will point you in the right direction.

Several times, various seasons
Things to do:
-Utrecht is a quaint town about half an hour train ride from Amsterdam. It is small with a happening, college vibe. Fun fact, it has the most bikes per capita of any city in the world. 
-The Van Gogh museum is spectacular. 
-Amsterdam is a great town for wandering, so put on your walking shoes and get lost fora day.  

-Amsterdam is fun for a short while but slightly overrated. It is geared towards the young tourist who wants to get stoned and party. I am not against this in the slightest, but the vibe gets old after a little while. It is also busy almost year round.
-Eat outside of the center of Amsterdam, you will get higher quality food for you Euro. 
-Book hostels in advance, they fill up quickly.

To ask me any advice or questions, contact me here. I would love to hear from you!