I am not really sure what you are looking for here. How does a horizontal view (Landscape mode in printing terms?) help if your summary is already very wide?
Some ideas to consider.
In a summary you cam specify that one key field should be displayed ACROSS rather than down the screen (and therefore printed output as well.)
You can usually change the width of the columns displayed - this may help but it does depend on the data in the cells being readable when you finish the width changes.
You could change the size of the font to get more columns and characters on to your screen.
Do any of these ideas help you?