There's on 6/13. From where can you see it and how bad is traffic in those hours?
Our recent guests went to watch a launch in May. They recommended Cocoa Beach. They didn't mention what the traffic was like though. I remember going a few years ago, traffic was fine all day, just closer to launch time we found parking harder as we had moved away to have a meal!
We watched the Atlantis launch in May. We headed towards Cocoa Beach, and as you go over the Causeway, with the port and cruise ships just ahead of you on the left, is where we went.
You need to go a bit further into Cocoa Beach, then turn around and come back so you can park on the other side. There is lots of space to pull off the road, and the local cops don't seem to mind as long as you're not blocking the traffic. You can get right down to the water's edge and look across to Merritt Island with a really good, unobstructed view of the launch sites...you can even make out the VAB.
Lots of people around us had radios, so we could hear the countdown and knew exactly when it was going to go up. Afterwards the crowds dispersed quite easily as you're on the major road in/out of Cocoa Beach.
We arrived less than an hour before launch, and still managed to find easy parking and a good spot. You can of course go to Cocoa Beach itself and some bars have good views but they fill up very early. Or Titusville has some good spots.