If you are lucky enough to catch a rocket launch, then Spaceflight Now can be a huge help .  On a recent trip to Florida I managed to see the launch of a Delta-4 heavy rocket.  The launch was a surprise and was pushed back several times because of technical glitches and weather.  Due to the nature of the payload – NRO spy satellite – the official sites had little details. Spaceflight Now had all the details and on the night of the actual launch had a play-by-play of the several restarted count downs.