Question
We are building a marketplace where tourists can get advice from travel bloggers.
There are a few modes of monetization we are exploring. One of them is a monthly membership to the platform. So, on our side, we are building a website, iphone and android app. The customers are charged whenever they want to have a conversation with the experts just as in "Clarity".
Answer
Great space to be in! I have been working with a startup in the Medical and Tourism business (where people go abroad to get expensive surgeries done more affordably). It appears that advice from US Govt. agencies, free blog subscriptions, 'lonely planet' and others is quite aplenty. I would suggest that your true monetization lies in offering exclusive travel deals through partnerships with hotels, resorts, airlines and the like.
Free ebooks from your top bloggers may also be useful.
In sum - create an audience, gain their trust, give them a deal.
Happy to elaborate more on a call!