My mother-in-law and her sons came to visit, and we took them here. She was about to have surgery to remove cancer, so it was a great option because (1) it's not too large, (2) it's close to all public transit options and (3) very tranquil. It was very informative, there were so many places to take beautiful family photos, and the garden even has its own tea shop, where you can enjoy some finger food and fantastic, educational, traditional tea service.
I HIGHLY recomend a visit here. Check out their website before coming because there are often special occasions built around Chinese holidays where they have storytellers, origami, etc.
Considering I was trying to find a destination that would entertain a 17 year old, 21 year old, and someone over 50, I was pretty impressed with my success!