Legoland- 1 Day or 2? - Azusa,CA

Unless you want lots and lots of time at their water parks you don't need 2 days. You can do it in 1 day, including Sea Life. Sea Life is super small and will only take an hour or so.
I do have one huge piece of advice though, bring an umbrella for shade. I don't know what they were thinking when they set the park up but there just isn't much shade, especially where benches are to sit. Those benches are limited. A very large portion of the park your baby will not be able to go on. The 2.5 year old may be too short for a lot of rides too. I would go onto their website and check the height limits for everything before you go. We had passes when my boys were 8,5 and my third was a newborn. We got very frustrated at the amount of limits on things. A lot of things are 2 person ride vehicles.
We would easily do what we wanted to at the park in one day.

Your kids are the perfect ages for Legoland! And for sure stay overnight, that will be so much nicer.
One day was plenty for us, but we went back in the day before they had a waterpark.
Personally I'd skip the waterpark and go to the beach, cheaper and cleaner (waterparks actually gross me out.)
Have fun!!!

2 days. Definitely. And so worth it! Have fun!

2 days. The water park is fun for hours There is so much for kids that age to enjoy. The line for the water park is long in the summer so plan on getting there early! Have fun! Well be there next week!

I personally would do 2 days if you are planning the water park. I have many times spent an entire day there with none of the water areas at all. I would skip the water park and just do the beach.