If you travel regularly, Tripit is a great service for organizing your flights and hotels on to your calendar (Google Calendar also does this with Gmail but it doesn’t work reliably, especially if you book some of your travel via your personal email account). You can set up a free Tripit account and either forward your receipts to it or let it look into your email for them automatically. Add the calendar of your Tripit trips to your work Google Calendar. These now show up in as a second calendar but are not visible to your co-workers. Create a free Zapier account and use a Zap to automatically copy all events from your Tripit calendar to your work calendar, which your colleagues can see. If you want to be shown as available while traveling, you need to change the multi-day event that Tripit creates from busy to available. And if you change your flights, you need to manually delete the old ones. But, people will no longer book you into meetings when you're on a plane.

Zap: https://zapier.com/apps/google-calendar/integrations/google-...