My wife and I will be in Amsterdam in late September and want to visit Arnhem before heading to Brugge. Option 1 is making Arnhem a day-trip from Amsterdam (by train or rental car). Option 2 is taking a train to Arnhem, spending a night, and taking trains to Brugge the next day. Any advice?
Make it a day-trip, it avoids one unnecessary hotel change. There are 48 daily trains between Amsterdam and Arnhem. Next day, you take a Thalys train from Amsterdam to Antwerpen and then to Brugge.
If you have the time or the inclination, in that area are both the Kroller Muller Muesum set in a lovely park with bikes you may ride, and the Open Air Museum. Both were worthwhile. We stayed a couple of days in the area. We liked the Hotel Sterrenberg in Otterlo, and used the easy local bus system to see these sights.
I agree with the idea of staying overnight near Arnhem. I also like the Hotel Sterrenberg in Otterlo--nice people, good rates, and very quiet. The nearby national park and Kroeller-Mueller Museum are gems. Just think, you can look at up to 50 Van Gogh masterpieces in the museum without hordes of fellow tourists. However, I don't know about the WWII sites near Arnhem. Public transportation is excellent in the Netherlands, but to save time, you might need a car instead.
If you have an interest in WWII sites in the eastern Netherlands, there is a great museum focusing on Operation Market Garden outside the town of Grossebeek (I am not sure of this spelling), a suburb of Nijmegen. This was the joint U. S., British, and Polish airborne operation in September of 1944 that included the battle at Arnhem. Another section of the museum illustrates what life under the Nazi occupation was like for typical Dutch citizens. I spent an enjoyable afternoon touring it a couple of years go when I was in the area for the Vierdaggse, - 4 Days Marches.
Having spent the night in Arnhem, I would encourage you to make sure of what you want to visit before planning the trip. I believe the "bridge" there is the third on that site since WW II began. Some imagination is required. For example, we passed a plaque on a building noting that it had been "gevorderd door de beruchte duitse sicherheitsdienst". But it's not in any guidebook I saw. Otherwise it's a rather modern town, with little trace of the war.