If you select a date for which there are no saver seats available, you get a calendar asking you to click other dates or switch to a Standard Award search.

Therefore, if your purpose is to view all of the fare buckets, you might as well start by looking for Standard. You'll see everything that way. In fact, I generally start my search on specifically the "prime" segment I want, taking notes and working outward from there, adding on the short-haul options once I lock in on the exact flights/seats I am most interested in.

If you're actually looking for Saver awards, by all means start there and use the calendar to filter to available dates.