If a company lists tour and travel packages on their site with proper price info and a link to book that package online, could such pages use the Product category from schema.org? As far as I know, the Product schema should only be used if the product is a tangible item.If not, should I use the Service category with nested Offer markups for such pages instead?
For tour and travel packages, should I use the Product or Service schema markups?
schema.org;structured data
If it has a price and/or if it can be booked, you have to use an Offer item.The item that gets offered could be a Product (this is not only for tangible things!), a Service, an Event, or a CreativeWork. I think in your case Event might make sense, but this ultimately depends on your specific case (your understanding of the tour/travel packages) and which properties you want to provide. Event is only appropriate if the date of the tour/travel is settled. If its instead something like a boilerplate, Product or Service should be used.Note that you dont have to provide an item for the thing which you offer. If you dont need more properties (and if you dont want to provide the additional data that something is an Event or whatever), you could use Offer only.Properties: Event/Product/  offers OfferOrganization makesOffer Offer inverse in case of Product/Service: itemOffered inverse: offeredBy