Mumtaz Mahal is a pretty good place with nice views if you are doing the tourist thing. It's a 15 minute drive from the Hyatt.
However, the best back street Indian restaurant in Muscat is Begum's in Al Khuwair, but there's no grog.
Any high end hotel in your area will have good Indian food as it is almost a staple here in Muscat.
As an alternative, I highly recommend Shiraz Iranian restaurant at the Crowne Plaza. Has it all, including a great view over the sea.