I have a small classification of cities:
1D city: cities in which you usually know where you are just by finding the main street or cities which are made only of one main street. Floripa (except for city center), Joinville, Goianésia, Bom Jesus da Lapa (BA), Ibotirama (BA).
2D city: cities in which you will find interesting spots if you walk in every cardinal direction. Brasília, City center in Floripa, Lisbon, Krakow, Hamburg.
3D city: cities in which you will find interesting spots if you walk in any directions, but also if you go up or down in metro stations, in underground galleries, etc. Barcelona, Berlin, SP, Buenos Aires, Kiev (YEEEEEESSSS!!)
Yes, Kiev is a 3D city!! And I have a certain tendency to be positively surprised by this kind of city the most. It is lively all the time, theres VERY cheap food, theres VERY expensive food, there are lots of foreigners, there is mafia cars going extremely fast in city center, theres all kind of people, and, by the way, a lot of each kind. =)
Officially my favorite city in Ukraine.