First night in Berlin
 

Any suggestions as what to do our first night in Berlin. Hope to be in hotel and ready to leave by 5pm. Staying at Berlin Intercontinental. We need dinner and a short activity. Restaurant nearby with tasty healthy food! Is it worthwhile to do a river cruise? Interesting area to walk that we might not see on our tours of area? Thanks for ideas!! Tried for Tower dinner reservations but none available.