I am about 45 min. from Disneyland, and April/May is my favorite time to go. The weather is beautiful this time of year, hardly goes above 80 degrees, and perfect for strolling around Disneyland. Also, it's after spring break, and before summer break. A lot of the schools have testing/finals, so people are less likely to take their kids out of school.
We just went to Disneyland last week and were able to just walk on a lot of the rides. There is always times where you have to wait in line, esp. for the more popular rides, but it's not nearly as bad as it is in the summer. We went on a Sunday!