The blog exists for inbound marketing purposes but also covers other topics under the travel umbrella - hotel/sights etc. Do you get to charge ad rates if it's not main media business? Ad charges as in for promoting posts/social media/newsletter pushout
You can definitely monetize your content charging an adequate ad rate. I would suggest to explore this option mostly after having built a relevant, unique and value added blog. If you manage to get qualified traffic to your blog (you can check this using any Analytics platform), you can then try to monetize this traffic, charging ad rates.
There can be several ways of tapping this opportunity, from selling advertising space via networks up to private marketplaces.