Hello,
I went on the Berlin city break last May, first holiday with JY. Had a fantastic time: the atmosphere was so relaxed and there is so much to see (historic points, buildings, museums).
Have you been reading up on the city? It helps to browse a guidebook or website, and have an idea of places you want to visit as there is some free time on the Saturday afternoon (if you opt not to go on the river cruise) and Monday morning for exploring/ relaxing.
Hope you enjoy your holiday!