Day trip Cologne

Day trip köln

Hi everyone, Im visiting köln as a dutch visitor with my friend (we are between 18-22)and visiting in october so sadly no christmas markets. We are getting there around 18.00/19.00. We would like to eat somewhere. Then stay the night in a hotel in the centre (preferably with parking) and then have a day in Köln. I saw that the zoo is pretty nice and that there is a chocolate museum. Also there is the clock tower ofcourse. Any tips? (Regarding a hotel, where to have breakfast, lunch and dinner and what to do?) Or maybe special shops we really need to visit? Thanks for all the suggestions