Ride a Big Boat down the Vltava: For those not willing to test their navigational skills or rowing strength in their own boat, large tour boats offer similar floating views, many with meals. Be sure to check the direction of your voyage to be certain it travels past the castles and palaces.
Picnic at Vysehrad: Of all the parks where you can picnic, the citadel above the Vltava standing guard over the south end of the Old Town is the calmest and most interesting spot close to the center. Its more remote location means less tourist traffic, and the gardens, city panoramas, and national cemetery provide pleasant walks and poignant history.
Spend a Day at the Zoo: Prague's zoo has improved immensely in recent years, after the 2002 flood severely damaged the grounds and even killed several animals. There's been lots of new investment and the setting by the river is great. Check out some of the biggest collections of giraffes and great apes in Central Europe.
Gaze at the Stars: For budding astronomers, Prague has two treats in store. A real live observatory on Petrín Hill is open on clear nights in summer or winter for checking out the moon, Jupiter, Saturn, and even some other galaxies. The planetarium in Stromovka park is an indoor stellar spectacle.
Hop Aboard the Oldtimer: That's Prague's endearing name for Tram 91, a vintage streetcar from a bygone era that still plies the rails on Saturdays and Sundays during the summer. Hope aboard at any stop, buy a ticket from the conductor, and ride for as long as you want.
Visit the Technical Museum: Older kids will enjoy a visit to Prague's National Technical Museum, a kind of miniature Smithsonian Institution, crammed with planes, trains, and automobiles. It's been closed now for several years while undergoing refurbishment, but was set for a grand reopening in 2010.
Get Lost in a Mirror Maze: There are lots of offbeat attractions on Petrín Hill in addition to the mock "Eiffel Tower." The mirror maze is an old-fashioned house of mirrors -- more disorienting for adults that it is for kids! But fun for all.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.