Airships are interesting vehicles, in that they are, as far as I know, the only ones to turn the square-cube law to their advantage. For a proportional increase X in length, width, or height of the gas bag, the lifting power of the airship increases by a factor of X^3.
Therefore, it would seem that, if you're making an airship, it's better to make one really big one rather than several smaller ones.
As of yet, I can only identify one problem with this, which is that more surface area = more space for wind to push on the ship. However, the effects of this on the ship's structure can likely be solved with aerodynamic design and modern materials, as well as using engines/propellers to counteract the force of the wind.
So - aside from potentially-solvable issues with high wind, what are the structural problems of an airship, whose lifting element is say, a cylinder a kilometer long and 175 meters in diameter?