There is a reason why this is a MUST-SEE in Prague. Not just the castle itself but the whole sureounding area is really nice with very neat green areas and great scenic views from the balcony. ????
Enter from the North side (see google maps) vice West and you'll face much shorter lines. Buy your tickets for Tour B a day ahead (250Kz), & then you can explore the grounds until the cathedral opens.
Make sure you get yourself to the tower to get the best seats in the house for the city of Prague! It's a 5 minute walk up the spiral stairs to get there.
Stunning place, really, everything here is so beautiful. Nice panoramic view of the city. Be sure to check out the gardens and enjoy the sun. The St. Vitus Cathedral is definitely a must see.