JotPlan

The most user-friendly scheduler might just be a printed Letter-size sheet with a month's worth of appointments. On paper, you're not confined to grids—you can write what's most important in a big way and fit plenty of smaller details. It provides an overview at a glance, and you can fold it up to take it with you. And if you flip it over, it doubles as a notepad.

You can do the same with JotPlan:

Your standard calendar appointments are displayed on the schedule. (You can also edit and add new ones.)
It follows a one-day-per-line format, so you have plenty of horizontal space to jot down anything you need on a digital Letter-sized canvas. (And if you can't fit it all, there's a notepad on the back screen.)
You can view the entire schedule in portrait mode on the iPad and zoom in on landscape mode.
What you write on the iPad can be checked anywhere using an iPhone.