Trip basically as Rick Steves guide tells it. The problem for my wife and I was her difficulty with walking. European tourist venues, at least by my limited experience, do not take into account the needs of people with disabilities nearly as well as in the States. Once you reach either castle, the walk in and out is a significant distance, all by cobblestone, which, I acknowledge, you encounter everywhere. For my wife, the walk was torturous. There should have been transport such as golf cart, to help those who needed it. I assume that THEY assume everyone can make the walk. After Kronborg, there was no way she could walk back to the train station, even though the Steves guidebook said the walk was short. True enough, for most people. We had taken a cab to the castle, but finding a cab to get back to the train station was fruitless. We still had to walk a considerable distance to catch a bus to the station, using our Copenhagen card, which, by the way, also covered train fares to and from Copenhagen. Great deal. Of the two castles, Frederickborg was by far the best. Kronborg, of Hamlet lore, was great on the outside, especially in coastal location. Inside much less so. Except for food, the Copenhagen card covered everything except taxis to and from our hotel to Centraal Station. This post is intended to help others of like situations for planning purposes. Viking River Cruises offers such guidelines in its side tour descriptions.
To be fair, I think your wifes difficulties with walking is your own problem, you certainly can't expect everyone else to solve that for you. When you visit a 400 year old castle your sould expect cobblestones. Golf carts to transport people around Frederiksborg Castle sounds a bit too much, if your wife has trouble walking short distances maybe you should consider getting her a wheelchair or some other sort of help yourself.
One thing I love about traveling to different cultures is that your perception about what is normal and the "right way"
to do things is challenged. In the US we have had the Americans with Disabilities Act for 25 years and accessibility has improved a great deal. It's not perfect. Many buildings are still not ADA compliant.
I have not been to Denmark since the 1980s so I know nothing about accessibility there but my observation in other countries in Europe is that accessibility is improving but that the US has done more in this area.
When you travel as a foreigner, you don't really understand how things work, so something like how to get a can is harder than if you are a local.
I can understand where the OP is coming from.
Of course, no country goes everything right. I envy the bike infrastructure in Copenhagen. We don't have any in my home town.
Thanks
as we all get older we will be needing to consider these types of difficulties . I know I have statedd taking more public transport. It sometimes was difficult to get hotel staff to give that info since 'its just 10 mins walk" - not such an easy ten minutes always