Hi, I know this is a 2-yr old thread, but in case someont is looking for an answer on how to switch from hosting to traveing in a webbrowser (not an app):
The only way I have discovered so far is going to messages, and then choosing the "traveling" tab (thus to see the messages that your hosts sent you in the past). Then the trips tab should appear automatically at the right upper side of the site and when you click on it, you are in traveling again.
Little bit inefficient, like everything on the new aribnb portal, but what do you wanna do? Obviously, a $1Bil.-company does not have money for a decent webdesigner...