Top down, thumbs up!
My husband and I took a 1hr. 2CV tour during our trip in January. While the weather may have been cold, we took advantage of the top down ride. It was such pleasant way to get an overview of the city. Our tour guide offered us so much insight into the city that we would have otherwise missed. I highly recommend this for anyone who is new to the city. It's a great way to learn and get a good lay of the land.