Rent a bike or Walk around/autos?

Me and my partner are planning for a trip to Mumbai and we have a full day for ourselves before others join us. We are planning the whole day around Colaba (Art galleries, Market, streets and Marine Drive). I want to rent a bike for a day but worried if parking will be an issue. Is it better to walk around or rely on autos? Or is bike a better option? Also open to any suggestions for cafes and other stuff we should check out in and around Colaba. Any help is appreciated :)