The tram is most certainly open on Sundays, or perhaps I should say on the Sunday that you're planning on. From May 20th through September 16th, the tram is open on Sundays from 1 to 5 PM.Of course, things like the aerial tram aren't open on Sundays, but the group did that last year at the Seattle gathering. So let us know if you're interested in joining us. Feel free to PM me if you wish. Hope you can come along!
Not saying that you want to ride it again, but it is certainly doable if people want.