What do I recommend / tell them - Travelers

Susan is 50 years old from Chicago, Illinois. She would like to travel to Berlin in the next six months. She’ll be traveling with her husband and their 21-year-old nephew who attends college in the US. They are planning to stay in Berlin for 4 days. It’s her preference to spend less money on accommodations so that they can “go big” on a few meals. They’d like to spend most of their time seeing off-the-beaten path sites in the area, but are hoping to visit 1-2 main tourist attractions the last full day in Berlin. The nephew is looking for some good nightlife spots to visit on nights 2 and 3.