In the Trip Planning page, you can drag and drop items into different sections. The first section is where you can throw in any ideas you have as you think of them. The other sections will be where you can add some organization or order to those items. Each section can be by day or activity, with the main section here still being location based.
Within these sections, you can also “like” activities, essentially showing your trip collaborators that you are voting on that activity for that day or in that location.
You can drag and drop locations too if you want to change around the order of the trip. Essentially, all aspects of the app (in the trips tab and functionality) are fully customizable.