My good friend Paul Schweizer sent me this list of activities for kids in Dallas. I added a few touches, but the list is mostly Paul's. The list is for brainstorming - but feel free to suggest descriptions and links for each activity.
Hiking on Trinity River
Biking and jogging at White Rock Lake
Tee Pee Hill Playground
Flag Pole Hill Playground
Merriman Park Playground
Pioneer Plaza
SPCA
Dallas Zoo
Fort Worth Zoo
Fort Worth Water Gardens
Science Place/Planetarium
Chuck E. Cheese / CiCi’s Pizza
Half Price Books flagship store
The airport
Dallas Nature Center
Dallas Arboretum (especially the toad fountains)
Feeding ducks at White Rock Lake (especially "sunset bay")
DART trains and buses
Lake Highlands North/Skyline Creek
White Rock Creek Greenbelt
NorthPark Mall (fountains, turtles, and ducks)
Dallas Museum of Art
The Nasher Sculpture Center
Dallas Public Library
Fairview Farms
Reunion Tower
Frontiers of Flight Museum
McDonald Observatory
Dallas World Aquarium
Dallas Museum of Science and Natural History
Dallas Children’s Museum
Dallas Recreation Centers
Train Museum at Fair Park / Frisco
Turner Falls (Davis, Oklahoma – visit website)
Big Bend
Main Event (3941 Central Expwy, Plano)
Dave & Busters
Medieval Times