I went to Disneyland in February, and we only had a day and a half to do both parks. Actually, it worked out well; we went to California Adventure on a Thursday evening and saw EVERYTHING in three hours (this included a sit down dinner!). We did Disneyland in a full day, and while we had to skip some of the attractions, we got done everything we wanted to get done. I believe you will have plenty of time to see everything in three days.