This is my decade and a half of travel. The list includes countries, airports, cities and towns from three continents. I have lived in four of these countries (three in Europe, one in Asia). I go to all the places that seem interesting, no matter how small. Trains tend to be the preferred method of travel, but occasionally it's cars, buses, ferries, planes or my own two feet.
Are you an active traveler or do you want to be? Check out www.nomadmania.com . It's the best traveler's site out there and getting better each month (app also exists). It's free of charge, unless you want to donate. They have meetings you can join (you can offer to organize one, too) and occasionally special travels to places where it's near impossible to get to.