Eh, personally I think it's more "exciting" to walk into the building at street level.

But for what it's worth, I bought 2 tickets online at 12 noon on Saturday for 1:30pm. We got there about 10 minutes late thanks to subway service changes, but there was really no line at all to speak of, and even the observation deck wasn't overly crowded. Was very pleasantly surprised, the whole thing was pretty well organized. That said, when we were leaving (which we did do via the underground concourse ), I noticed the security line was a bit longer, but probably not more than 10 minutes.