Staging your DVDs on disk is a great idea. Oracle gives you a script (adautostg.pl) to help you create the right structure so that rapidwiz goes smoothly.
However, you should verify that adautostg.pl actually copies all the files on the DVDs correctly. For example, I had two disks that didn't get completely copied and I received an "AC-00023: Error: Exception: java.io.FeilNotFoundException: filename" when I installed for the first time. After I compared my media with the staged directories, I found out that some files on my DVD were corrupt and didn't copy.
To fix this issue, I had to download the affected disks from http://edelivery.oracle.com