Seven days are more suitable for two cities, or one city plus surrounding mountains and waters. You can enter Beijing and leave Shanghai and establish a system, but every travel day should be deliberately light.
Organize the route with two anchor points
First, choose a historic city and a contemporary city, then decide what each person most wants to experience. Don't force a third stop just because it appears on a classic map.
Keep arrivals and departures relaxed
On the first night, stay a bit closer to the hotel, and don't force the big attractions in the last morning. This buffer will help maintain the rhythm of the entire week.