The LA house of mouse is part of my life. I don't like it but there it is. I had the most amazing date there...Tom Sawyers island...
Many years later I took my then wife there for her first experience...she was raised back East and had never been. When our kids arrived we bought the SoCal season pass for a couple years...when they were still reasonable ($200/each). So I have spent some money there.
By far the best time to go is during the Christmas holidays right before everyone takes off. The park goes all out on decorations, the mood is really festive, and the weather is great. No lines or waiting is what you are looking for. As others have already stated it's worth it to take the kids out of school for the day or two, take a couple days off work, and go when others are busy.