Heres a few more suggestions for the next Quark 6.x/7 version:
1) Build in a descent object scale feature, that can scale up or down items at a specific percentage or to a specific dimension(s).
2) The PDF creation could also be beefed up abit, by adding: a) security options, b) a progress bar when the PDF is being created, c) put the Create PDF option directly in the File menu and NOT as a sub menu.
3) Add more standard page formats into the new document window, eg. A5, A3, A2, A1, and B1-5 as well.
All I can think of for the moment... 8)