Google Assistant will soon allow you to check in to your flight and save your boarding pass. If your flight confirmation is in Gmail, the Assistant will send you a notification to remind you that check-in for your flight is available, or you can say "Hey Google, check in to my flight". Once you've checked in, you can view your boarding pass in Google Pay or say "Hey Google, show me my boarding pass."
Once you've arrived where you're going, you might need a place to stay. Google Assistant can help with that, too, helping you to book a room at a hotel. You can say something like "Hey Google, I'd like to book the Cambria Hotel in New York on January 12" to view availability and pricing. You can even reserve a room using your Google Pay payment options.
Google is working with hotels like Choice Hotels, AccorHotels, and InterContinental Hotels Group as well as online travel agencies and partners like Priceline, Expedia, Mirai, and Travelclick - an Amadeus company on this feature. It's currently available on Android and iOS smartphones in the U.S.