City to visit after Amsterdam?

For our honeymoon (in April), my fiance and I are going to be spending a few days in Amsterdam, then a few days in another city. We want to go somewhere that will be a nice contrast to Amsterdam, maybe somewhere warmer? We have considered Marseille/Nice, Lisbon, Barcelona or Paris. We are very outdoorsy and would love to go somewhere that has beautiful nature to explore. We are also big art and architecture nerds so places with beautiful architecture or art museums would be good. Europeans of reddit, any suggestions?