Like many here I also had an Trip Planner idea, also because I was solving my own pain point, to accurately create a feasible schedule for trips. My MVP (which is actually my travel planner) is a simple Google Spreadsheet that uses Google Maps API to calculate drive times between destinations (I like to do car trips). So i simply use it to put each destination, calculate driving tim and time at destination to fit the most destinations inside a day. It could become a product if it had access to a huge destinations database (like tripadvisor, Gmaps, etc.) with infos like "estimated visiting time", cost, etc... But I came to the same conclusion as Garry, this wouldn't be something that would appeal to many people.

Here is the link for the spreadsheet for the curious (you'll need a Google Maps Api key): https://docs.google.com/spreadsheets/d/16T9kLpbqciKCLNWOoOV1...