If you go to Prague you must see the castle. However, this is not the most exciting of visits. Save the money for circuit A and get smaller circuit B. We got the guided tour from the castle guides - it was very very basic. You are better off having your own guide or using an audio guide.
Views of the fort are great as is the walk up if you use the Charles bridge approach.
We had a tour guide who was very friendly, accommodating and detailed in providing information about the Castle. He even had a map of the castle as we walked along and provided information with gusto and a welcoming smile.