Disclaimer: I have never been to
Legoland.
That said, I *have* been to SW several times, and would definitely recommend two days for a visit. There's lots to do to keep you busy for two days, you would be able to take in all shows and rides at a leisurely pace, and you would have the opportunity to feed the animals and check out all the great exhibits without feeling rushed. While you could hit all the highlights in one single day, I personally would want two to "see it all".