San Diego Zoo is bigger than SG Zoo afterall, hence the higher price is to be expected. And it has more variety than SG, its like a stamp book collection there, everything from koalas to pandas...
And btw, we may never get to see gorillas in SG, really sad... some funky soil disease here is fatal to gorillas, and humans as well. No cure has been found yet.
SG Zoo has advantages though, much more close contact than any American zoo can ever dream of having. Elephant rides, getting close to orangs, even walk-in exhibits can never be allowed in America, apparently because zoos there are afraid of lawsuits from visitors.
Oh, and we have the night safari too... that trounces San Diego!
Would love to go to Okinawa aquarium to see the whale shark. Their gigantic fish tanks makes our sentosa underwater world look like a puddle. underwater world really needs a makeover, its not worth the admission.