I'm originally from Orange County and with a 1 year old I would do Disneyland, as opposed to CA Adventure. The coolest things about CA Adventure are the bigger rides. Yes, your DD may enjoy the Bug Life and what not, but i think Disneyland will be more interesting (and more to do in general).
Oh wait, do you have a choice of going to the other park?
Well, if not, I would just walk around CA Adventure, go to the Bug thing, do the car ride through LA (or whatever it is), get a beer, and just kind of relax. It is a more relaxed theme park in my opinion, and since you won't be spending a lot of time standing in line for Soaring over CA or the Hollywood Tower rides, you will have a lot of time on your hands. Oh, and check out Downtown Disney while you are there. The Rainforest Cafe is a fun place to eat, but not very original.
You are also close enough to Knotts Berry Farm in Buena Park (15 min up the 5 freeway, transition to 91W and exit Beach Blvd). It is also a theme park, smaller, lots of big kid rides, but also home to Camp Snoopy, which is perfect for younger kids.
Discovery Science Museum in Santa Ana is not far from D-Land, and very fun. My daughter was about 16m old when we took her there and she loved it. There is also a zoo in Santa Ana that my parents took her too, and they had fun. She rode a camel there (or so she tells me).
Have fun!
Audrey - Feb 2010
Anderson - Dec 2011
Please, no babies in 2012!