The route from Luzern to Interlaken. This is the Brünig Pass line, and is part of the route marketed as the Golden Pass line.
Sit on the right leaving Luzern. You have 2 out of 3 lakes on your right, and the view as you go over the Brünig Pass.
When the train changes direction at Meiringen, you are then on the left which is the lake side for the second part of the trip.
The Gotthard panorama route takes a boat from Luzern to Flüelen, then the train from there over the Gotthard pass. The boat is scenic but slow. You could take the boat, then at Flüelen (the far end of the lake) get a train back to Luzern.
Edit: I have just noticed you say "from Interlaken to Lucerne". Are you starting from Interlaken or Luzern? If you are in Interlaken, then getting to Flüelen involves going via Luzern and is a long way for a day trip.