Saint Petersburg & Moscow

In SPB you can visit some parks around the city (Peterhof, Gatchina, Tsarskoe Selo, Oranienbaum) and also some parks in the city - starting from the famous Letny Sad (The Summer Garden).

Also you can walk around the very city center along the channels because most of the major Petersburg streets is planned to show direct view of big landmarks as Admiralteystvo, Petropavlovskaya Fortress, biggest cathedrals and so on.

Speaking for Moscow is completely different story.
Unfortunately, Moscow lost most of her historical landscapes, now protruded by modern buldings (usually not so good - i say, as Moscow architecture historian;-).

But you can catch some beautiful landscapes, for example starting from sounth-west part of Moscow middle-area - Vorobievy Gory - the place where Moscow State University skyscraper stands. University surrounded by parks and also has a nice (but i prefer another, less touristic) observation point.
Across the Moskva-river, closer to center stands Novodevichy monastery - amazing (and pretty well preserved) example of old-russian architecture of XVII century.
Also you can shoot Moscow Kremlin from the bridges across the river - but it's most obvious and dull way.
In the east of Kremlin another interesting place you can found - junction of Moskva and Yauza river with another stalinist skyscaper and, a little upper on the Yauza river, another big monastery - Andronicov.
You can alos visit some parks of XVIII century closer to borders of Moscow (Kuskovo, Ostankino, Kuzminki etc.) - it was a country residences when Moscow was much smaller.
Other advices and point of interest to visit depends much of your tastes - more old-russian things (like a churches or monasteries in Moscow Region - Archnalgelskoe or Zagorsk) or more soviet "empire" things (VDNKh (ВДНХ) exhibition complex, Noth River Station and main streets) or late soviet modenistic city-scape or contemporary view of collage city.