Insight Vacations has an eight-day Easy Pace Russia guided tour (from $2350; flights not included) that visits St Petersburg for four days, including visits the Winter Palace, St Isaac's Cathedral, Fortress of Peter and Paul and Peterhof Summer Palace, and three days in Moscow that includes visits to the Red Square, the Kremlin Fortress, Lenin's Mausoleum, St Basil's Cathedral and the metro station, known as "the palaces of the people" with their chandeliers and marble columns. The tour also includes train travel "Soviet-style" between the cities and stays at the St Petersburg Crown Plaza hotel and the Hilton Leningrad Skaya in Moscow. Contact your local travel agent.
The best way to get around the centre of this historic city is to walk. For longer trips, hire a private car and driver or a taxi with a meter at your hotel (avoid flagging down taxis on street); or take the metro — it's cheap, clean and safe, has some beautiful historic stations, and is the deepest subway in the world.