I am trying to find an easy way to separate multiple pages
in one visio file into separate single-page visio files.
Does anyone have any ideas?

The following code works for me. It copies the page in the active window
to a new document.You must adapt page height and width and perhaps some
other properties too.

    Dim doc As Document
    Dim sel As Selection
'select all shapes in active window
    ActiveWindow.SelectAll
    Set sel = ActiveWindow.Selection
' and copy selection into clipboard
    sel.Copy
' add new document
    Set doc = Application.Documents.Add("")
' get first page
    Set newPage = doc.Pages(1)
' rename it
    newPage.Name = "NewPage"
' now the active window shows the new doc
' paste the clipboard into it
    ActiveWindow.Paste

Hope this helps
  Stefan