You're adventurous going to Lucerne on an 11 hour layover. Take an hour to get off plane, get bags, store them, and find ground transport, plus another 3 hours before boarding, so you're now down to 7 hours. Trains would be 2-3 hours return, so you're down to 4 hours in Lucerne. Doable, but 7 hours of faffle for 4 hours of enjoyment? Up to you.
If it were me, I would stay in Zurich. I love Zurich:
a) the Swiss National Museum is adjacent to the main train station;
b) walk through the old town to the lakefront. See the outrageously expensive shop windows. RS Guides have a good walk through Zurich;
c) take a 90 minute lake cruise on the Zurichsee;
d) walk back along the Limmatt River to the Fraumunster and/or the Grossmunster;
e) walk back along the riverside Limmatquai back to the station.
Whatever you choose, enjoy!