Try Day One, an awesome looking journaling app for both Mac and iOS. Think of it as a facebook timeline for your thoughts, but visible to only you on your own device.
It has pretty simple features like a uploading photos, calendar view, reminders for writing, quick search, export as PDF and lot more. You use even use markdown to format the text. It automatically syncs via iCloud or Dropbox, so you can view your journal on any of your Apple devices.
Though it is ideal for any kind of creative writing, I think it works best for maintaining your food journal, movie reviews or even as a dream log (yes, thats what I am going to use it for, to record my dreams).