May 19, 2015 - 5:59 AM
Your schedule for the day with Lake Brienz, the Aare gorge and the falls (I'm not sure which ones you mean) looks quite full. I wouldn't plan an additional evening trip if I were you. You can best check traveling times in the timetable to find out how long your journeys will take. If you do want to make a train ride, you could indeed travel along Lake Thun, either all the way to Thun or from Spiez to Zweisimmen and back. That's certainly scenic.
The general route from Lucerne to Zurich is nice, but not particularly scenic. If you have time, you could travel a part of the Voralpen Express, which heads north-east from Lucerne, before actually traveling to Zurich. You could go as far as Wollerau along Lake Zurich, for example.
Tips for activities in and near Zurich can be found on our Lucerne page.