Something that should be noted here is that by purchasing tickets through Viator for a certain day does no mean guarantee you an admission on that day. I had pre-booked my Space Needle ticket 6 weeks in advance, and turned up at 4:30pm on the day to head up - only to be told all remaining slots were sold out and I'd have to return tomorrow. Thats what I did - it opens at 9am and I arrived at 9:20 due traffic - only to be told that the first slot was 12pm. I explored the Chihuly gardens while I waited well worth it - the sculptures are incredible and returned to the space needle lifts at 11:45am. One thing that also isn't mentioned is that it isn't free reign up and down the needle - you have to line up for the lift over a 45 minute wait! before even getting up top. I ended up bailing on the space needle as I was venturing to the museum of flight later that day and didn't want to waste time in lines. My advice is get there early! Or avoid the space needle on weekends/holidays otherwise you will walk away frustrated instead. There was only one poor guy redeeming/selling tickets and that was also a significant wait 20 mins even after purchasing them here first. You can purchase tickets at the bottom - that would save you time sounds weird huh? You would think online would save you time...