One very easy day trip from Nyon is to hop on a ferry across the lake to Yvoire, France. Expect an afternoon full of meandering lanes that lead you down toward a castle and active fishing village or up the hill towards gardens and tourist shop after tourist shop. It makes for a truly lovely day, feels so much more like France somehow, and offers many options for a gourmet meal or just a really nice Haute-Savoie lunch at Flores.