You will find a whole row of cafes open to the sky on the first level of the city shopping center. What is interesting about cafe life is that many young people either drink juice or "schweppes" -- it's a bit for money reasons I think -- but at least the group I know see going out as a chance to talk & be with friends rather than to drink to excess.
The shopping center Leptakarija is just a 5 minute walk or so from my family's apartment. It is a nice shopping center at the base of a group of 7 story apartment buildings. It is full of cafes and restaurants.
I often meet friends at Cezanne cafe.
There are two main "rows" of cafes in Skopje. One is inside the main shopping centar -- the other is along the Vardar. The street was recently pedestrianised so now the cafes are spilling out closer to the Vardar. It makes for a very pleasant place to sit and have a coffe or beer.
New York Cafe is on the new pedestrian area next to the Vardar River. It is very attractive and a choice of many Skopeans for that expresso or macchiato. [everyone's fave right now]