We visited Lucerne last year and it was incredible - although very expensive, definitely worth a visit.
Unfortunately the first day we arrived the weather was terrible so visibility was very low in the mountains. We had a good day walking around the town taking int he sights - definitely enough to do there for a full day. The second day was glorious and we managed to go to the peak of Mount Pilatus, which was just breathtaking and definitely a tick off our list.
Lucerne is the only place we visited in Switzerland so I can only comment on here, but I can totally recommend it!