Mumbai (Bombay)
Gateway of India - The Gateway of India, built by the British and completed in 1924, is a triumphal arch in a Gujarati palatial style. This famous landmark in Mumbai is also a great place for kids to just watch the boats go by in the harbor. Come early in the morning, grab breakfast at the Indigo Deli, walk down past the fancy Taj Mahal hotel (another architectural extravaganza) to the Gateway.
Prince of Wales Museum - Visit the Natural History section of the Prince of Wales Museum, where they have a wonderful exhibit of birds and animals native to the area. You can easily spend several hours here.
Ride the double decker bus - Bombay is worlds away from London, but kids love to ride the red double decker bus around the Fort area.
Nehru Science Center and Planetarium - Check out the Children's Science Park, an outdoor area with things to push and pull, plus mechanical stuff such as a railway engine and old tram car. Inside, there are many new science galleries, exhibits about the technological contributions of India, plus the Planetarium with sky shows.
Marine Drive (Netaji Subhash Chandra Bose Rd.) - In the evening, take a ride along the sea in a glittery horse-drawn carriage.
Kamla Nehru Children's Park - Popular with local families, visit this children's park, and climb up the Boot House (looks like "there was an old lady who lived in a shoe"). From the park, there's also nice views of Marine Dr. and the beach. Across the road, also check out the Hanging Gardens (Ferozeshah Mehta Gardens), with lots of sculpted plants and flowers, gushing fountains.
Northern Mumbai -
Bandra Bandstand - Bandra Bandstand is a long promenade along the ocean that begins at St. Andrew's Church and goes north. There are two parks along the promenade, one has swings and slides, the other is just grassy areas.
Bandra Fort - Bandra Fort, located right on the ocean, was built by the Portuguese and has been newly restored. Get a sandwich across the street and have a picnic - there are grassy areas and benches.
Juhu Beach - Much less crowded than other beaches, it's clean and a nice place to play. Just don't get into the water.
Water Kingdom and Essel World - If the heat is getting a bit much, head to Water Kingdom, a large water park with children's slides, shallow pools with water toys, as well has high speed slides for older kids and teens. Essel World is an amusement park with rides.
Sanjay Gandhi (Borivali) National Park - Just 40 km north of Mumbai is this National Park, a jungle in the metropolitan area, where "you may see some very fat, very lazy lions" along with spotted deer, macaques and langur monkeys, crocodiles, and many species of birds and butterflies.
Tip: In the morning, get an early start, and do your sightseeing until noon, then start again in the late afternoon. Avoid the hours between 12:00 - 3:00 when it's very hot and hectic.
Fun food
Buy fresh coconuts to drink the juice. Idlis (rice cakes), dosas (like a pancake) are great snacks. The best chocolate milk is at the Bombay Baking Company in the Hyatt (and a nice place for a break).
For a special lunch or brunch in an atmospheric setting, try Gallops Restaurant at the Mahalaxmi Race Course. The restaurant serves Indian as well as Western style dishes and has plenty of kid friendly food. Brunch is served on the lawn on weekends. (Go early to ensure a table.)