Balboa Park Casa del Prado — Photo courtesy of San Diego Convention & Visitors Bureau

San Diego's Balboa Park is the nation’s largest urban cultural park and there is quite a bit for all ages to enjoy. Admission to the park, individual gardens, the Botanical Building and Timken Museum of Art are always free. Between gorgeous grassy areas to walk, hike, picnic and sunbathe, you can easily spend an entire day in Balboa Park without actually setting foot inside the park's highly-regarded museums.

For something closer to the sea, try Torrey Pines State Natural Reserve.  Located on the beach between La Jolla and Del Mar, the park boasts breathtaking ocean views, 8 miles of hiking trails and guided tours on the weekends. Stop at the Visitor's Center to learn about native plants, animals and geology in this 2000-acre park. Then, have a picnic lunch on the beach. A vehicle fee of $10-15 applies.

The C&O Canal begins in Georgetown, a historic neighborhood in northwest D.C. — Photo courtesy of Laura Padgett It would take you weeks (or longer) to properly explore one of Washington, D.C.'s coolest parks. The Chesapeake & Ohio Canal National Historical Park runs a whopping 184 miles from end to end. Starting in Georgetown and extending northwest to Cumberland, Maryland, the park follows the path of the old canal as it wends its way along the Potomac River.

In the 1800s, the canal moved coal, lumber and crops to communities along the river. Today, the activity continues in the form of runners, hikers, cyclists, kayakers and more.

For history buffs, there are tours of lock houses and other historic structures. Or, do a little time travel yourself and take a mule-drawn boat trip down the waterway as park rangers dressed in period clothing regale you with tales of long-ago life along the canal.

Crown Fountain at Millenium Park, Chicago — Photo courtesy of Chicago, Illinois

The Crown Fountain in Chicago's massive and popular Millennium Park provides entertaining fun for young and old.  Two 50 foot towers facing one another on a reflecting pool project video images of 1,000 different Chicagoans.  Watch as the faces make different expressions for five minutes, spending one minute spraying water from an outlet that appears to be coming from the mouth.  Kids can splash in the water and watch in amazement.  This $17 million installation, opened in July 2004, is a part of Chicago's public art collection.

Also, be sure to head to the Family Fun Tent in the Park's Chase Promenade North for free concerts and family activities daily.  Live music and dance performances, hands-on arts activities for the kids and a reading circle are some of the things offered for your child to enjoy.

Portland, Oregon's Forest Park — Photo courtesy of Mike Rohrig

Portland, Oregon is home to one of the largest urban forests in the country, Forest Park.  Stretching over 8 miles and receiving over 40 inches of rainfall a year, this park is a haven for over 62 mammal species and 112 bird varieties.  If getting back to nature is your family's thing, this is the place to be.  Flying squirrels, deer, elk, tree frogs or salamanders are just some of the things you might see while walking these beautiful paths overlooking the Willamette River.

For more kid-friendly parks with play structures, Portland Walkdorf School has a neat rope spider-like web for climbing.  Laurelhurst Park is one of the most beautiful with a wading pool, stone climbing wall, picnic areas, duck pond and lots of green space for frisbee throwing.  Sellwood Park is where to go for outdoor swimming and playground equipment for all ages.