JW Marriott is big and well placed on the beach. The buffet is legendary (in Bombay). It's in
Juhu which is a very trendy part of Bombay, where the Bollywood stars live. If you have to be in just one place for work then always choose a hotel close by. Even 'close' will normally mean at least 30 mins in a car. If you haven't been to BOM before, brace yourself for the traffic...
Grand Hyatt (Santacruz) and Leela are great. If you need to be nearer to Powai, Marriott Renaissance in a decent new room overlooking the lake is also pleasant.