Ok, just had a look at the search feature. Definitely a candidate for Views and I don't really see any need for custom coding at the moment.
Each location would be a piece of content (called an accommodation or something intuitive). I'd have fields to cover all the important bits and I'd add location fields so that you could geocode each "accommodation" in case you want to show them on a GMap or something as well. For the criteria in the search, I'd create taxonomy lists for each section (type, location, facilities) and finally, I'd build a "view" using the Views module that would allow searching and displaying the results. Even the listings from the menu (hostels, campsites, self-catering, etc...) would just be links to a view that would take the appropriate attributes and deliver the appropriate results.
* Views is that general purpose module I mentioned earlier that allows you to create displays of content based on either fixed criteria like, content type: posting date, taxonomy terms, filtering if various fields (titles, body, etc....) or user selected criteria from text fields or drop-downs, radio buttons or checkboxes.
I think I'd use the feeds module to import the content into the site by exporting it to a CSV file, massaging it a little and then importing it. That can be a little tricky to get right but it's generally more efficient that entering manually.
As far as ease of use for the owner goes, I've built a reputation for building Drupal sites that are easier to manage than Wordpress. It's not difficult to do. You just need to configure the site with the right WYSIWYG tools, create editing roles with reduced access to admin areas they don't need and offer some training.
That looks like a cool project.