It was one of the early Mars missions, we were with the crowd in the main public viewing area, the launch pad was a mile or two away, and the roar and vibration was overwhelming. And this was not a Saturn V, but probably an Atlas or something similar.

I saw several Saturn V moon missions go up, from Tampa, about a hundred miles away, including the one Dan refers to, but all I could see was the rising star of the exhaust and a contrail.

I can see launches here in S Florida, even though the Cape is about a couple of hundred miles away, but they are very low in the north.

The most spectacular launch I've ever seen was from Vandenburg AFB, I was observing and had my telescope set up on Alpine Road, on the ridge between Palo Alto and the Pacific, between San Jose and San Francisco. I wasn't expecting it, I am an amateur astronomer and I had set up my 8" reflector there. It was probably a military launch, because there was nothing about it in the news. They launched north, and I watched what must have been a stage separation almost directly overhead. Of course, I didn't get a chance to put my scope on it, but even as a naked eye event it was phenomenal, and very colorful.