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This design has good error prevention. Each field that the user fills in (locations, hosts, dates, etc.) will give suggested completions. Fields will be checked and only accepted if they make sense (real locations, hosts and a timeline that makes sense). Also, every action that user makes can be undone, whether that includes changing locations, changing hosts, or changing dates. The user will be alerted if the change is inconsistent with the rest of the trip that is planned.
Design 2:
(1) This design starts with a login. Victor would login by pressing the "Login with Facebook" button. This page doesn't have much except a login button which is very simple and learnable. Not much about efficiency or error prevention.
(2) Welcome page (for a first time user - Victor). It talks about the application, what it does, etc. After reading, Victor will click on the "Design a Trip" button to begin planning a trip. This page, like (1) is very simple and learnable with little about efficiency or error prevention.
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