We usually go to a place called Paul's Smokehouse, it's a popular venue with lots of people, but the view of the site is about as good as you can get without one of the on-site tickets.
Google Map of The Restaurant
Ashley and I have been to 6 or 7 launches at this point, both day and night, each one had its own flavor. Night launches are really sweet. If I had one word of advice, it would be that a solid set of binoculars are a much more enjoyable way to watch the launch than through the lens of a camera. Every time I've taken a camera, even one with a good zoom lens, I've spent more time worried about getting a shot than I have enjoying the spectacle. Trust me, a professional photographer with a superior lens and unmatched access will get a good photo of the launch that you can see on the internet just hours after it happens. See it with your own eyes, not an LCD screen or a tiny viewfinder.
The last time we went was a night launch, and I had a pair of fairly strong binoculars, and I didn't take my eye off the shuttle for at least 3 minutes from takeoff to well past booster separation, long after everyone else had lost the tiny dot of the main engines. It was simply beautiful.