[LifesGreatestGift]

Add the following code to additional.css template

/* Quick Reply Editor */
#cke_contents_vB_Editor_QR_editor {
    height:300px!important;
}
/* Quick Reply Editor - END */

/* Go Advanced Editor */
#cke_contents_vB_Editor_001_editor {
    height:450px!important;
}
/* Go Advanced Editor - END */

As of right now, the height of the boxes are hard-coded in clientscript/ckeditor/ckeditor.js

Change variables to suit your needs.