Suzhou works best as one full day or one overnight from Shanghai. Staying overnight gives you quieter mornings before day-trippers arrive.
The easiest heritage extension from Shanghai and a good contrast to a megacity.
The classic garden; reserve early in busy periods.
Canals, snacks and evening atmosphere.
A strong architecture-and-history stop.
Landscape, history and an easy half-day.
Best after sunset if you enjoy lively heritage districts.