First time in the Netherlands, some suggestions based on our itinerary please

We'll be in the Netherlands on the 30th of December for 3 nights and we're looking for a few recommendations based on our itinerary please.

We're based in London and always go away for the New Year (my partner is a teacher so we're stuck with school holidays) and we love Central and Eastern Europe around that period. We had left it a bit late this year but found some cheap Eurostar tickets to Rotterdam and when realised most cities are within easy reach of each other we thought it'd be a good option.

We'll spend the first afternoon and the first night in Rotterdam and then we found a nice hotel in Utrecht for two nights, we want to see the city but also use it base and won't spend our whole time there.

We thought about spending half a day in Utrecht to see the sights and have a wander around and then maybe visit La Hague and Leiden too (we have been told Amsterdam will be so busy over that time and warrants another visit another time). Do you have some suggestions in terms of cafes, restaurants (we love hearty Central European food) and just things to see apart from the more obvious ones please? We definitely want to to try some breweries in Utrecht.

A bit about us and what we like: we love history and architecture (old but also new when interesting hence we are curious about seeing Rotterdam), food, walking around.... To us travelling isn't just about the sights but also experiencing the vibes of some interesting and less visited cities. For example we absolutely loved Ghent, more than Bruges as it felt like such a nice, liveable city and I really like its university city vibes.