A 1-hour boat tour gives an overview of Amsterdam's UNESCO canal ring and architecture; most operators run from ~9:00am–10:00pm. Book in advance for peak season.
Traditional Dutch windmills, clog-makers and cheese farms are open roughly 9:00am–5:00pm; reachable by a short train/bus from Amsterdam Centraal (20–30 minutes).
Iconic Gothic cathedral facing the Rhine; cathedral access is free but tower climb has a fee and limited opening hours (tower climb commonly 9:00am–5:00pm).
Medieval castle and the famous cathedral painting are Ghent highlights; castle usually opens around 10:00am—check opening times for the cathedral's viewing hours.
Allow at least 2–3 hours for transfer plus check-in/security if flying; train to Brussels Airport takes about 20–30 minutes from Brussels-Midi or Central.