Hi Patti,
The MTR only stretches as far as Chai Wan, unfortunately, but tonnes of buses ply the routes to the more remote south part of the island. Try to get a double decker bus and sit on the top deck at the front - you'll have a great view as you traverse the rolling hills

The 16X bus goes from Chai Wan to Stanley - it's about a 15 mile journey - but it might be a more breathtaking ride from Causeway Bay (also on the MTR) to Stanley, as it takes you up and over the mountain and through Repulse Bay to Stanley. The bus ride is a tourist experience in itself!
Would be interested to hear of any changes you see - I always had the impression that Stanley was stuck in a timewarp - in a nice way!
Here's the MTR map for your reference. As you can see, it's quite extensive.