To find Disney land or Disney world NOT busy, you have to go when the school is in session.
When I lived in Arkansas, the school our kids were in let the kids out for the first two days of deer season (the second monday and tuesday in November). So we took the entire week off and went to Disney world. We were able to wait less than 5 minutes for Space Mountain. As were getting off the ride we decided to go again. So we walked down the exit ramp and back up the entrance ramp. When we got to the where they put you on the ride, the people in front of us were just being buckled in. We walked to the next car and got in and away we went. No wait at all.
I hope you have lots of fun. Good luck to you and yours.