First .... Transfer any and all purchases into iTunes that you have made with the new iPad - even free apps and content - transfer all of it into iTunes. Backup the iPad one last time as well.
Disconnect the iPad from iTunes and go to Settings>General>Reset>erase all content and settings. Wipe the iPad that way instead through iTunes.
When you get the new Mini you can restore from the iPad backup at the end of the activation process, sync with iTunes and the Mini will have all of the content that the iPad had on it.
Read these for more information.
How to backup and restore from a backup
Copy any purchases of the iPad to your computer's iTunes via File > Transfer Purchases, and then force a backup of it by control-clicking the iPad 'device' on the left-hand side of iTunes and selecting backup on the popup. You should then be able to restore that backup onto an iPad mini (though if you updated the 4 to iOS 6.0.1 you may also need to update the imini to that first).
You can restore the 4 back to factory defaults directly on it - first log out of your account on it by tapping on your id in Settings > iTunes & App Stores and then do Settings > General > Reset > Erase All Content And Settings
Backups and restores : http://support.apple.com/kb/HT4079
Thanks, Demo. Already have all purchases in iTunes since that's where they all emanated from over time, anyway (nothing was every purchased from iTunes directly from any of my iOS devices).
I was going to do one last backup also, but I hadn't thought of doing the reset from the device itself...thanks for that. Now when I activate the new iPad Mini it should be able to use the restore (after I tell it that's what I want to do). Thanks.