Mumbai city including its suburbs is a big city. It is very crowded and traffic is very heavy, so traveling in Mumbai is extremely time consuming. Depending on how many days you will spend in Mumbai and what your priorities are it is suggested that you split the sites area-wise.
If you have one day then start with you have one day then start with South Mumbai city
Early morning: Drive to Gateway of India. The driving time will depend on which part of the city you are staying. At the Gateway you can hop in the motor launches available down the steps and take a tour of the harbor. Tickets are available at Gateway of India.
Elephant Caves: From the Gateway of India you can go to Elephanta Caves. The same launches conduct tours to Elephant Caves. Tickets can be purchased at MTDC counter (Maharashtra Tourism Development Corp), at Gateway of India.
Launches run between 9.00 am-2.30 pm (closed on Mondays) from Gateway of India. It takes 45 minutes to reach the island. The launches leave the island for the return trip back to Mumbai between noon and 5.30 pm. The trip to Elephanta Caves can take anywhere between 4-6 hours. So plan accordingly.
Lunch break: There are a number of inexpensive restaurants near Gateway of India and Colaba Causeway.
If you have some time after lunch you can either shop at the Central Cottage Industries Emporium near Gateway of India, which has Indian handicrafts, jewellery and ethnic wear at reasonable prices OR at the roadside stalls or small shops lined along Coloba Causeway.
After lunch: Visit the Prince of Wales Museum which is very close to Gateway of India, on M. G Road.
Open between 10.15 a.m. to 5.45 p.m., Tuesday through Sunday, closed on Mondays.
There is a Rs. 5/- entrance fee for adults.
This museum tour might take a couple of hours.
Late evening you can either walk on the Marine Drive promenade or just take a taxi ride from Nariman point to Malabar Hill, to see the lit up Queen's Necklace.
If you are staying for two days then visit the "must see" places in North Mumbai.
Early Morning: Drive ( by taxi or auto rickshaw) to Borivali suburb of North Mumbai.
(Note: Even though it is very convenient, do not travel by the local suburban trains on weekdays, as the trains are extremely crowded at any time on weekdays.)
You can visit the Sanjay Gandhi National Park (7.30am-7pm Tue-Sun) and Kanheri Caves (9.30am-5.30pm Tue-Sun) before lunch.
One of the main attractions of Sanjay Gandhi National Park is the lion & tiger safari.
At Kanheri caves there are 109 caves used by Buddhist monks as a monastery between 2nd and 9th century.
Lunch at: It is a good idea to pack some snacks or sandwiches as there is only one restaurant near the park which is the Park View, Near Sanjay Gandhi National Park, Shantivan, Borivali East.
After lunch take an autorickshaw and drive over to the west side to Gorai Beach. From Gorai Beach you can get a special ferry that will take you across to Essel World.
It is open between 11 am to 7.00 pm all days and upto 9.00 pm during school holidays.
Entrance fee is Rs 125/- for adults and Rs. 100/- for children.
Here you can spend the rest of the day relaxing in the green landscape around or enjoy the rides or cool off on the water rides of the Wet World.
If you have one more day. You can either take it easy (as two days of sight-seeing in Mumbai can be very exhausting,) or do some shopping around Mumbai, as Mumbai is a shopper's paradise. Mumbai has a number of western style multi-storied shopping malls. It is worth visiting the Chor Bazaar area, located near Mohammed Ali Road, which is famous for antique and vintage items. Another place for shopping is Bandra Linking Road a shopper's heaven with streets lined with stalls and shops selling everything. Bear in mind that bargaining is a must in Mumbai.