The only one on the list that I have been to was Lisbon. I traveled alone but it was for STEEMFest last year (which was extravagant)... I had an awesome time and loved the city. So much to see. It's a quaint and charming place (and you get a great leg workout from the steep streets).

ohhh and can't forget the Pastel de Natas! Creamy & Delicious ;)