For Adults:

1. Visit the Flight 93 Memorial
2. Enjoy performances at the Marga Gomez Theater
3. Shop at Union Landing Shopping Center
4. Explore the Sugar Mill Landing Park
5. Golf at Skywest Golf Course (nearby in Hayward)

For Kids:

1. Play at William Cann Neighborhood Park
2. Visit the Union City Library
3. Enjoy the playground at Sea Breeze Park
4. Have fun at Pump It Up of Union City
5. Explore the Dry Creek Pioneer Regional Park

For Both:

1. Hike at Garin Regional Park
2. Attend events at the Union City Sports Center
3. Explore the Alameda Creek Regional Trail
4. Visit the Ardenwood Historic Farm (nearby in Fremont)
5. Enjoy the Union City Street Eats food truck events

These activities offer a mix of educational, recreational, and cultural experiences suitable for both adults and children in each city. Remember to check for current operating hours and any potential restrictions before visiting.