Yes, saw the castle. Seven day trip went roughly like so:
Arrived Friday night. Saturday- general walk around town to get oriented, up to Castle entrance and back to Old Town square (our hotel was 5 minutes away). Evening concert at Smetana Hall in the Obecni Dum (the beautifully restored Art Nouveau municipal 'house') Sunday- Castle: St. Vitus cathedral, Vladislav hall, St. George, Golden Lane, and a walk through Stare Mesto Monday- National museum most of the day (rain)- lots of geology, some paleotology, zoology and archeology; train station and walk to National theatre Tuesday- TV tower, Vinohrady district, Fred and Ginger, Jean Nouveau 'Angel' building +shopping center; royal gardens, Loreto, castle and parliament entry area, St. Nicholas Church Wednesday- Alfons Mucha museum, St. Agnes Museum (medieval to Renaissance Czech art), 1905 exhibition hall, Troja Palace Thursday- New town hall, river walk, Stare Mesto and Devil's brook area, Rudolfinium, Jewish Quarter (briefly) Friday- Jewish Quarter, Old town square- departure.
'Fred and Ginger' (Gehry building) basically sucked with respect to the unbelievable amount of well detailed turn-of-the-century eclectic and Art Nouveau buildings. Nouveau's shopping mall was straightforward and nothing special.
Marcello