Local taxi's were very reasonable at OMR10 per hour and in 3 hours you can pretty much see on the main sights. Lovely walk along the corniche all the way to Old Muscat in less than 1 hour. ...
the town section near the cruise port is the most interesting part (old souk, closed between 1:00 and 4:00 pm), I do not recommend to walk to the town 5 KM it has many Gov. buildings and schools , no commercial activities (practically no cafe no stores) and you the streets are empty.
FYI you cannot walk in the port, a free shuttle will take you from the ship to an administrative building ...
Only the market near the port is good. We took a taxi to the hilltop for the view, then went to the palace, but it is PERMANENTLY CLOSED to the public.
The museum opposite the palace is overpriced at 5 Omani rial per person, while local senior citizens get FREE entry.
The beautiful mosque in Muscat is very far from the port & taxis wanted a whopping 20 Omani rial for a round trip! ...
We walked to the Mutrah souq on our own (easy walk...once you exit the port go left and continue walking until you seen the entrance to the souq) on the first day. On the second day we booked a rental car and took a taxi to pick it up at the Al Bustan Palace Hotel (about a 15 minute drive away -- we paid 5 OR for this taxi ride although the first drivers wanted 7 OR...given that if you are hiring ...