Mid January is a great time to do Disneyland as the crowds are not a big as some of the other months. I think it would take 1.5days to do Disneyland and 1 day to do the California Adventure Park. 1 day for San Diego Zoo, 1 day for Legoland (I haven't done Legoland but have friends there at the moment and they did Legoland yesterday and spent almost a full day there, they liked it better than Disneyland) and 1 day for Seaworld.

I wish it was me who was going! Have a great time!