just a suggestion. it aint no 5th avenue and central park but this is hong kong. HV is green, it is open. it is commutable. not only the race course is green, either side of the valley is pretty green. yes, there is a 8' high concrete wall surrounding the race course, but at least wong nai chong road is planted with big old trees.
I'm sorry, i meant 15 mins on the mtr. I assumed if OP can accept 45 mins, he can spend 30 mins from happy valley to get to the MTR. The #10 bus works quite well to central.
I spend a lot of time in my apartment looking over the race course so it feels very green and open when you live there. As for race nights, thats the sacrifice i that. its not that bad. i quite enjoy having tourists in my neighborhood every wednesday night.