Canada to ski and for vacation several times. USA many many many times.
Mexico.... wow, what a wonderful place!
Bermuda - Bahamas Booooooooooooooring
Cuba.... twice, the world's best beaches (Varadero)
Guatemala - Belize - El Salvador - Costa Rica - Panamá
Colombia That was a nice place, loved it.
Venezuela
Peru with MSF, helping in a quake aftermath
Chile - Argentina I hated Buenos Aires.
Brazil (one single night, I was in transit)
UK (Scottland was nice, and Wales was a drunkness spree, I loved to see the Queen in that balcony)
Spain ... Y Olé!
France, Oui, Je vais te faire un p'tit calin.
Belgium: Waffles, chocolate and 5Kg weight gained...
Luxembourg: tax-free paradise!
The Netherlands: weed lollipops are awesome, but I cannot remember anything.
Denmark BORING
Sweeden: Transit, Tack sa mycket.
Norway: Et lite onske.
Estonia: 





Italy (therefore the Vatican) - Switzerland - Austria - Liechtenstain - Germany Good trip.
Czech Rep - Transit, but Prague is awesome,
Poland, at the border towns only, Wadowice was a must that time :P
Serbia - Croatia and Bosnia & Herzegovina: got impressed by the Sarajevo roses
Hungary - Bulgaria -Romania: cool places, if you ignore their social problems... I was there with the UN youth program
Moldova: I was illegal in that place, for two days. :P
Greece : amazing Mikonos :P
Turkey: should NEVER join EU
If I'm missing one I'll tell later, I'm too lazy now.
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I'm a damn Doc, don't question my word.