We chose a tour company mentioned in the RS guide book - [email protected]. The owner is Jana Kratka and she arranged our booking with Michaela Vlachova who was very enthusiastic and very personable. We booked a four hour tour with her that did not include the castle. We chose to tour the castle on our own with audio headsets. This worked out great as you would need more that four hours to tour the castle with a tour guide.
Michaela showed us more than the highlights - she pointed out unusual facts about the areas we saw. I had told her we were interested in seeing some bead shops and she took us to an outstanding shop that did not appear in any of the searches I had done. Michaela really knows the city and her English is impeccable.