Scheduling date ranges or specific times
Roll over the item in your Notebook and click "Add to Itinerary" in the balloon. (Or if you've already scheduled the item, click the scheduled date that appears in the balloon.) Then in the itinerary dialog, click "More Options" at the top right.
In the itinerary dialog, you can choose an end date. Check "All Day" for items without a specific time (like hotel stays), or leave it unchecked to set the start and end times and timezones.
Scheduling separate events
Planapple also supports multiple itinerary events for a single item -- if, say, you're visiting the same place on two different days.
First, schedule the item for one of the events -- by dragging it to the calendar, or by using Add to Itinerary as shown above.
Then to add the next event, click back into the itinerary dialog for the item. At the top of the dialog is a menu that lets you add or edit specific events. Choose "New" from that menu, and pick the second date to schedule for the item. (Click "More Options" if you want specific times and timezones for the event, as shown above.)
You can repeat this process to add additional itinerary events. To edit one of the events, pick it from the menu and make any desired changes. Or click "Unschedule" to remove it.