Petrin Hill (take the funicular, get off at the stop half-way up the hill, there is a restaurant with a view) or Hradcany (Metro station Malostranska, walk up the stairs to the castle, stop just outside the castle entrance) will serve for a sunset shot across the river. The television tower in Zizkov might also be worth a look, it's certainly tall enough and there is a restaurant thingy halfway up its stalk... take the metro to Jiriho z Podebrad. Shots up the length of the river Vltava with its bridges in full view can be taken from the Metronome monument, in Letenske Sady. Or you can go the old fortress at Vysherad for the opposite view.
At last someone who can remember and spell the metro and tram stops. The restaurant at stop on on the funicular is rather good, I never recall the tram stop on that side of the river to get off to find it, so I have to ask. There is a great pub, Husa, on Vinohrady up the hill from Jiroho Z Podebrad Metro, on the right, I am thinking the Green line, order the Cheese Plate-- aged Czech cheeses. Everything on the menu is rather good, beer is very fresh there.
Tram 22 takes you the longest, and I think it takes you up the hill to Prague Castle.
There is an art museum behind the Jewish Cemetery on the street that runs along the river, and though they ask you not to shoot photos in the Cemetery, there is a great view over the wall from the men's room window in the art museum.
If you are at Malostranka, and cross the square and street on the bridge, there is a small park below with a good view of the Charles Bridge, the river, and hopefully some swans. Sometimes called "Joe's Place" because of a well known photo taken there by Saudek.
I have been to several Sudek museums, but his studio has never been open, but I have not been back for a couple of years. I would probably visit anything associated with Sudek.
Nice island / park, up stream from Charles Bridge, take the stairs down from the bridge.
Very important Czech phrase, Prosim Pivo.
J