It may be worth mentioning that at least one RL commercial company is trying to repopularize airships (aka blimps or Zeppelins):
Airship Ventures
You can take an hour-long tour of the San Francisco Bay Area from Oakland airport for $495.
To recap what others have suggested, the difference between timelines where dirigibles became popular than in our own timeline might be nothing more than better weather on May 6, 1937.