We recently returned from visiting WW2 sites and I wanted to recommend both a hotel and several places to visit -
The hotel - Landgoed Hotel and Restaurant Groot Warnsborn, Bakenbergseweg - a few miles outside of Arnhem city, nestled in the forest but very close to Oosterbeck, a mansion converted to a hotel. Rooms are in both the main building (ask to see the rooms - some are lovely, some are under the eaves with slanted ceilings); the newer buildings are better - the coach house is recently renovated and would be a very good choice . Grounds are lovely and I cannot say enough about the restaurant - really excellent, as good or better than meals in France! We were on half-board and greatly enjoyed both the generous brunch buffet - breads, cheeses, meats, etc) and the fantastic dinners, which were generally French/European.
The sites -
Fair - Airborne Museum Hartenstein/Villa Hartenstein. 2 mi from hotel - the house used by the Brits during Market Garden - very crowded, poor description, audio-guide poor - we were not impressed
Very Good - Airborne War Cemetery, Oosterbeek, set in beautiful/ quiet surroundings, very evocative.
Good - Arnhem War Museum/Arnhems Oorlogsmuseum 2 mi from hotel - lots of tanks, guns, etc; staff are very good - enjoyed hearing of their families experiences during the war
Excellent - Vrijheidsmuseum/Freedom Museum, Groesbeek 45 mins from hotel follows the war from beginning to end, with emphasis on impacts on the Netherlands (occupation, Margaret garden, etc) - one of the best museums we've been to - stayed for several hours
And - very different and VERY interesting - The Bronbeek Museum, Velperweg 147 6824 MB Arnhem, - tells the story of the Dutch colonies and the wars for independence - in English and Dutch - with films, artifacts, audio-guides - really excellent!!