Its depend upon your budget. If you wants inexpensive than you can take four beded room in aproximately 2600/- Inr Near Airport & if you take like that room in city with standard hotel will cost around 4500/-.
In Juhu Beach, the Marriott is nice. In Colaba, much cheaper, the Ascot is very clean and very accessible to the sights (15 minute walk to the Gateway of India, close by interesting shops). My detailed posting on the Ascot including photos should appear in three or four days. Their website is www.ascothotel.com and the photos they post, though small, are accurate.