Word Travels is one of the longest-established travel content providers and it licenses it destination information to airlines and travel agencies. See more information on what they can provide here: Travel Content Licensing
I believe Frommers - the American travel guide publisher - license their guides to airlines etc, but I am not sure if this is still the case since they were bought by Google. They have now been sold back to Arthur Frommer and license his content back to him! So I assume he cannot now license it on to other companies. Lonely Planet also license their guides.
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Travel Content Licensing