Dover is a port before it is a beauty spot. The town has taken a century of traffic and looks like it. The cliffs are why you came, and they are a short bus or a walk east of the harbour, not a backdrop you admire from the ferry queue. On a clear day France is a fact, not a metaphor.
Come for the cliffs and the castle. Do not judge the country by the retail park beside the docks.
See
The White Cliffs
The National Trust land at Langdon Bay, or the coast path toward St Margaret’s. Walk far enough that the port drops out of the foreground.
Dover Castle
English Heritage, and a full half-day if you go in. The secret wartime tunnels are the modern history. The walls are the medieval one.
The harbour, briefly
Ferries the size of housing estates. Worth ten minutes so the cliffs have a scale.
St Margaret’s Bay
The next bay east. Smaller, and the right place to sit if the wind allows.