You could physically visit both the zoo and SW on the same day, but you'd be having a rushed, mediocre visit at both places. Those are two parks that each require a full day to get your money's worth.
So for 2 days we'd have travel time of about 90 mins each way. Well. May not be so bad. How do the shuttles work? Are there preset times to and from hotel? Or can you come back when you're ready?
but my family spent 8 hours at the zoo last Thursday. And we STILL didn't see every single exhibit! We arrived soon after the 9am opening. We saw the koalas and pandas early. We walked & walked more. We took the Skyfari and then did the bus tour. We walked some more. It is a great zoo, but I was tired by the end of the day!