Prague Castle

This tour has great reviews:

https://www.viator.com/tours/Prague/Prague-Castle-Walking-Tour-Including-Admission-Tickets/d462-9396P1

Thank you Lane. We think something that’s starts in the morning might be a good idea.

Check out The Naked Tour Guide at www.nakedtourguideprague.com. We did a morning breakfast tour with him. It was excellent. I know he does an evening Prague Castle tour. Enjoy Prague! What a great city.

Viator are just resellers and do not actually run any tours.
the aformentioned Naked tours are a good company and run small group tours.
https://www.livingpraguetours.com/
this company also does small group tours but only covers some of the castle are but they also do private tours so worth asking them .

The best way to experience Prague Castle is at night. We (Naked Tour Guide) run at tour at 8.15pm because it is the best time to go there. If the best time to go there was two in the afternoon, then I would run a tour at 2pm.

The best time to experience the interior is at 7am, when it opens for mass. You get to see the building being used for its intended purpose, without the detrimental effects of 1.7 million tourists.

Thank you all for the suggestions

I booked a one hour tour for my wife and I when we visit in September - it is through the Dept of Tourism within the Prague Castle Administration. It includes St Vitus Cathedral and the Old Royal Palace - the rest of the buildings and exhibitions we are on our own. I believe Jason from the LivingPrague.com site recommended it.