Hi Saloni, Indore is known as the street food capital of Central India. You should definitely walk down the Chappan Dukaan and the Sarafa Bazaar to experience it. Here is a food guide for you:
Indore Food Guide: Best Budget Eateries for a First Time ... In addition, you can visit the Rajwada and shop your heart out in the surrounding lanes. You can also plan for half a day trip to Ujjain which is one of the 12 Jyotirling and is just a couple of hours from Ujjain. Besides the Mahankal temple, you should also visit the Kalabhairav temple and the Jantar Mantar which is nearby.
Rajwada is a historical palace to visit.. just beside and behind that, there is Sarafa (jeweler market in day, food street from night to late late night 8pm - ~2am) and there is local market offering a lot of stuff for shopping. There is a kanch mandir (walls are beautifully decorated and covered in glass).
Chappan dukan is another food street open all day. Do try Vijay chaat.
For temples - Gomatgiri, hinkargiri are few which are huge and calm. They are a lil farther than airport at small hill. Khajrana is also very renowned Ganesh mandir. Natural places near by: Mandav, Choral, kalakund, patal pani.
Ujjaini has water sports but I didn't visit there..
Regional part was developed by govt. I went there some time back.. Chowki dhani, nakhrali dhani are themed attractions offering family hangout places.
Crescent Water park is also good one. Mayak water park is relatively older. Zoo is also renewed.. Enjoy the cleanliness and colorful painted walls on street.