Why do half the cities in Canada have one of those giant needles with a restaurant on top?

Global warming. Once the ice on Greenland and in Canada melts they need a safe place to sit it out. In the event the water comes higher than the tower's height, explosive charges at the foot of the tower will go off so the "restaurant" becomes a flotation device while the (hollow) tower itself will act as a stabilizer.

Never watched MIB?

Is this default scenery you're flying over? I only ask because I've never actually visited most of these cities, other than from the driver's seat of a semi passing through. Needless to say, the view is a bit nicer from the airplane's higher altitude.