One low-key day trip from Lucerne would go to the Rutli Meadow - by boat - where the Swiss Confederation was born - nothing much there but could get off the boat and back on the next one.

The Swiss central bank has jacked up the price of the Swiss franc about 20% - thus if buying Swiss Passes be sure to check for the price of the exact same pass in $ bought in the States before leaving - usually pass prices in dollars are slow to rise along with the exchange rate but anyway in light of this sudden re-evaluation check prices both here and there IMO. RailEurope and their agents wholesale/retail these passes - RE being part owned by the Swiss Federal Railways.