My two usual spots are the USS Texas Battleship Park as mentioned by Bob and another good spot is/was the little spot at Morgan's Point. I say was because from a previous thread
here it would seem that Morgan's Point is undergoing some security "enhancements" like a fence to keep out people who like to fish from the end of the point and of course, shipspotters.
Of course, the security angle is a bit of a farce as like Bob says, the USS Texas Battleship Park has plenty of parking and even nice benches facing the channel. Personally, I'm thinking the fence is being used to keep the hobby fishermen from driving by the ritzo rich houses. Mustn't have the wrong class passing through one's neighborhood, must one?
That aside there is also a nice little park at the free Lynchburg ferry not to far away to the east of Battleship Park. It is also visited by the aforementioned so called lower class fisherpeople and shipspotters. No fences there, either.