We are heading for Zermatt, but have two days (at least one of which is expected to be rainy) beforehand to visit either Lausanne or Lugano. We would appreciate your opinions as to which city is the better sightseeing choice, especially if one of the days will be rainy. Thanks!
A strange pair of cities to consider, opposite directions from Zermatt. I can't imagine where you could be coming from that would throw up those two as options.
And, they are opposite sides of the Alps. The weather is usually different on the two sides of the Alps.
Lausanne (on lake Geneva) is in western (French speaking) Switzerland. It is Switzerland's 5th largest city. It rises up from the lake, the whole city is on the side of a hill. You get good views over the lake, but otherwise it has city attractions.
Lugano (on lake Lugano) is south of the Alps, in Italian-speakung Ticino. The climate here is usually is warmer, and sunnier, than north of the Alps. Lugano is my personal reccomendation. It has an italian flair about it, and a picturesque setting on the lake. Take an excursion on the lake, then you can look out from the boat if it is wet. Another option is to go up the mountain which overlooks the city (Monte San Salvatore).