I agree with PPs to choose Disneyland over Legoland (this coming from a lifetime member of Legoland!). When DD was 2, we could not do much at all. There are so many height requirements (the lowest is 34") and a 2 year old would only be able to do the 3 rides that do not have a height requirement. There is a slow-moving water ride and then the lake tour. There is a really cool big playground (with a little train that he would be able to ride)., and some fun music things to do. Then there is a little toddler water park but in January it will be way too cold for that. Otherwise the other rides all have heigh requirements.
I was amazed after spending so much time at Legoland when I visited Disneyland for the first time with my kids. My then 2 year old could do almost ALL the kiddie rides. It was fabulous!!!! Come to Legoland when DS is 5 or 6 and you will get WAY more bang for your buck. If you do decide to visit Legoland, you can get pretty cheap tickets on ebay for about $30-35 each. Members get free passes and sometimes people sell them. They are issued at the end of December for the following year.
DD (3/05) and DS (5/07) still harnessed and loving the cupholders in their Frontier 85s!