Really it's booking.com is worth ~$95B and the rest of those brands combined are worth ~$5B (OpenTable just got written down from an accounting perspective).

There is a huge general misunderstanding in the profitability of directing hotel bookings vs flight bookings or other types of travel consumables. Rate parity and high commission rates mean that directing hotel rooms is hugely profitable and Expedia (hotels.com, trivago, expedia) and Priceline (booking.com) operate as a duopoly in most markets. They are both marketing machines that turn brand + paid traffic into highly profitable room nights.