I really like this last version.
I dunno if i am sure, but guess is some details/ divisions in the roofs will give some "reality irregularity".
I loved the idea of Zeppelins, i just can imagine how it will be. Just a idea, to not forget the high levels buildings for VIP airlifts. Some ppl will like to go to labs, political centers and events using Zepelins what will give a medieval hi-tech touch.