Istanbul: Mocha & Baksheesh
Buy this firstBGG rates it 7.88 from 3,415 ratings. A BGG poster says that if you buy only one Istanbul expansion, buy this; others call both expansions good but not necessary.
Needs: Just the base game
Adds: Four new places to visit, more interaction between players, a coffee good and new ways to earn rubies via the tavern and guild hall.