Hong Kong MTR Subway (Airport Express)

My family is going to Hong Kong next month and we're looking for the best options to go from the Hotel Novotel Citygate to our Hotel in the Kowloon (Novotel Nathan Road).
I know that the Taxi fare is around 250 HKD between the two locations, the ride takes around 45min and the taxi carrys 04 people with small baggage in just one cab.
The Airport Express MTR Subway Line costs around 50 HKD/person between Tung Chung and Jordan stations and takes around 35 minutes.
We would like to have a view of the Hong Kong Area from our Cab or Train during this ride, just too see a little be more about the islands and the areas that we won't visit during our trip.
So my question is: Does the Airport Express Subway runs inside tunnels (under the land) or outside (over the land)? What about the taxis, I imagine that 90% of the ride is outside, right?
Have a good one guys!
Cheers!