I didn't know the Run class.
With your code, I was able to complete my generic method.
For those interested, here is the code:
Private Sub SetColumnWidth(ByVal pTable As Table)
Dim arrSize(pTable.Rows(0).Cells.Count - 1) As Single
Dim sngWidth As Single
For Each myRow As Aspose.Words.Row In pTable.Rows
Dim intCol As Integer = 0
For Each myCell As Aspose.Words.Cell In myRow.Cells
sngWidth = 0
For Each myRun As Run In myCell.GetChildNodes(NodeType.Run, True)
sngWidth += CSng(myRun.Text.Length * myRun.Font.Size * 0.6)
Next
arrSize(intCol) = Math.Max(sngWidth, arrSize(intCol))
intCol += 1
Next
Next
For Each row As Row In pTable.Rows
For intCol As Integer = 0 To row.Cells.Count - 1
row.Cells(intCol).CellFormat.Width = arrSize(intCol)
Next
Next
End Sub