As a Dutchie I have visited some of the Dutch (former) royal/ noble palaces, houses etc. Certainly not all of them.
But I have also visited some abroad. Due to time, costs or my travel companions I haven't seen all from the inside. Some even only from far

Still it is nice to see both the difference as the similarities, even between countries

Over time I have seen,
among others:
Netherlands- Het Loo Palace, Apeldoorn (exterior and interior)
- Noordeinde Palace, The Hague (exterior and park)
- Lange Voorhout Palace, The Hague (exterior)
- Warmelo House, Diepenheim (exterior) (former house of Princess Armgard, the mother of Prince Bernhard)
- Dam Palace, Amsterdam (exterior and interior)
- Tilburg Palace-Council House (exterior) (Willem II)
- Soestdijk Palace, Soestdijk (Baarn) (exterior) (former house of Princess Juliana and Prince Bernhard)
- Drakensteyn Castle, Lage Vuursche (Baarn) (exterior) (former and current house of Princess Beatrix)
- Bronbeek, Arnhem (interior and exterior/current function as living quarters for veterans) (once intended for Queen Anna Paulona)
- De Haar Castle, Haarzuilens (Utrecht) (Barons van Zuylen van Nijevelt)
- Doorwerth Castle, Doorwerth (interior and exterior)
- Twickel Castle, Twickel (Delden) (exterior) (currently Counts zu Castell-Rüdenhausen)
- Almelo House, Almelo (exterior) (Counts Van Rechteren Limpurg)
- Doornenburg Castle (Doornenburg) (exterior and interior)
- Hatert Castle (Nijmegen) (exterior)
- Sint Hubertus Hunting Lodge (Otterlo) (exterior and interior)
- Binnenhof (The Hague) (exterior and interior)
- Mauritshuis (The Hague) (exterior)
- Stadhouderlijk hof (Leeuwarden) (exterior)
- Doorn House (Doorn) (exterior and interior) (last residence and resting place of Emperor Wilhelm II of Germany)
Abroad- Vianden Castle (Vianden, Luxembourg) (both count and royals) (interior and exterior)
- Royal Palace Luxembourg (Luxembourg City) (exterior)
- Bourscheid Castle (Bourscheid, Luxembourg) (exterior and interior)
- Royal Palace of Brussels (Brussels, Belgium) (exterior)
- Bouillon Castle (Bouillon, Belgium) (exterior and interior)
- Amalianborg (Copenhagen, Denmark) (exterior)
- Buckingham Palace (London, UK) (exterior)
- Blarney Castle (Irish: Caisleán na Blarnan) (Blarney, Ireland)
- Sanssouci Palace (Potsdam, Germany) (exterior and interior)
- Schloss Charlottenburg (Charlottenburg Palace) (Charlotteburg, Berlin, Germany) (exterior and interior)
- Dresden Castle (Dresden, Germany) (exterior)
- Munich Residenz (Munich, Germany) (exterior)
- Saint Emmeram's Abbey (Regensburg, Germany) (exterior and partly interior) (Thurn und Taxis).
- Imperial Palace of Goslar (Goslar, Germany) (exterior and interior)
- Bentheim Castle (Bad Bentheim, Germany) (exterior and interior) (Princes of Bentheim-Steinfurt)
- Cochem Imperial castle (Cochem, Germany) (outside and inside)
- Anholt Castle (Anholt, Germany) (exterior and interior) (Princes of Salm-Salm)
- Schloss Wittgenstein (Bad Berleburg, Germany) (inside and outside) (Princes of Sayn-Wittgenstein-Berleburg)
- Wernigerode Castle (Wernigrode, Germany) (exterior) (Counts of Stolberg-Wernigerode)
- Donaueschingen Palace (Donauschingen, Germany) (exterior) (Fürstenberg)
- Monschau Castle (Monschau, Germany) (exterior)
- Castel Sant'Angelo (Rome, Italy) (Vatican) (exterior and interior)
- Apostolic Palace of the Lateran (Rome, Italy) (Vatican) (exterior and interior)
- Castel Gandolfo (Castel Gandolfo, Italy) (exterior and part interior) (Vatican)
- Prague Castle (Prague, Czech Republic) (exterior and interior)
- Louvre Palace (Paris, France) (exterior and interior) (currently expanded museum)
- Luxembourg Palace (Paris, France) (exterior)
I was in Berlin before the real reconstruction of the Berlin Palace took place, at that time still indicated with canvases.