Correct me if I'm wrong, but you used to be able to get a lot closer, until after the Challenger.
I don't think so. I've seen over a dozen launches since I was a little kid back during the days of Apollo. We've watched from a number of different areas, but I can't ever remember being closer than a mile.
There were two different launch pads that were used. The Challenger was either the last to use the old one, or the first to use the new one. This might be the cause of some of the confusion. Also, I think that they've now gone to a third pad as their primary launch site. These are all slightly different distance from the viewing galleries.