We went on Labor Day in 2012, or around then. We were there before and after. We went to Disneyland the first day on Labor Day because I specifically wanted to see some things that were going to be closed immediately afterwards. Indiana Jones and Casey Jr and Storybook Canal boats were all being renovated after Labor Day, so we saw them and then when we went later in the week it was no big deal that we couldn't go on them. So check the Disneyland site, they'll tell you when a ride is expected to be shut down, that's what we did.
The weather was beautiful in Anaheim that time of year, but while we spent three days total in between the two parks we also found time for Hollywood, Warner Bros. Studio tours, the different beaches, swimming in the ocean and Universal Studios. Don't fly down for just 4-5 days, take at least a week, if not more. Disneyland is worth the trip alone but there is so much more.