We bought the $20 ticket and went on Wednesday December 23rd. We took the advice of the ticket seller and went at 5pm. There was no line up, we literally walked onto the 2nd pod, although the entire facility is set up to service long, long, LONG line ups. Luckily, we just walked on.
So at 5pm it was dusk, the perfect time to go. We saw so much of the strip - great views. Entire experience was 30 minutes. We enjoyed it. I'm glad we got the $20 tickets - as a Canadian, and with the terrible exchange rate right now, full price tickets would have cost me approx $52 Canadian - and I wouldn't have paid that.