We were there last week at AK on a day with crowd levels of 3 (out of 10, on the touringplans scale).
Two Rivers of Light shows were scheduled. We showed up 10 minutes before the first show and easily found seats (granted, they were at the far end of the seating areas -- the center sections were pretty full at that point and CMs were guiding everybody to the end sections, although if we'd chosen to disobey them I could see seats still available in the middle that we could have snagged). When the show started, there were still open seats all around us -- I'd say the benches were, at most, 90% full.