I stayed here last year, very Central and clean, great value http://www.hotelcauseway.com/, costs about 300-400 rps in a taxi from the airport.
The Gateway is just around the corner and the Taj hotel, good for a day out to Elephanta Island. There are some good bars in the area and plenty of local colour and some great restaurants too.We hired a taxi for about 4 hours costing 400 rps and he took us round quite a few places, Chowpatty(better at night), Malabar hill, towers of silence, Dhobi ghats, Malaxmi racecourse, cricket ground and finished at crawford market.

Mumbai Hotels can be very expensive, in bad areas or rubbish for the money so go with the recommendations

For anyone who's interested there is an article in the Daily Mirror travel section today about Mumbai.It gives a few ideas of things to do, and also mentions a place that does a walking tour run by an ex accountant from England and his Indian partner, it costs 400 rps and takes 2 1/2 hrs.
http://www.realitytoursandtravel.com cheers Keith

We did the Dharavi Slum tour with this company in January and I would strongly recommend both this tour and the company.
Dave

Hi Roma,
We got the pre paid taxi from the airport (around 400 rupees) We stayed in The Residency Fort Hotel in April (INVALID URL It was pretty central. The rooms are small but clean and it's very handy to a lot of the tourist sites and within walking distance of good restaurants. The staff were very friendly. Depends on your budget. You can pay a lot more. We would stay at the Residency again. We thought about booking tours but we just did it ourselves when we got there. There are loads of taxis and we did a lot of it on foot. We loved Mumbai and may stay for a few days next year on route to Goa or maybe we'll try Bangalore. Mumbai is very busy and after 4 days it was nice to fly to Goa to chill out.
Hope you get a hotel to suit you.
Gail

Hi Roma...
if you have not already...purchase a copy of Lonely Planet India...very helpful...full of good hotel...tips ...places to go and things to do whilst in Mumbai...(also covers ALL of India).

Hi Roma we are staying 3 nights in Mumbai on our return from Goa in Dec
have booked the Residency Fort it was recommended by Irish Coleen & Hubby
report on H/T hotels
annx

Thanks very much for the suggestions everybody! Now for some research and I guess the Lonely Planet Guide may be a good investment - my Rough Guide to Goa must be about 10 years old!

Thanks again