I just stopped by to say the same thing HydroGuy. First step, do not use TouringPlans for crowd prediction. I personally don't like it for WDW either, although I know many do, but you definately don't want to use it for your DL trip. The Lines App is OK, as HydroGuy said, but I think most agree that the crowd predictor is far from accurate.
Choosing what day to go to which park is not as important at DL and it is at WDW. I would strongly suggest you park hop, as the parks are a hundred paces from each other as opposed to an hour waiting for then riding the bus to another park at WDW. I regularly hop back and forth several times over the course of a day.
Perhaps the more pressing concern in selecting a day to go to DL would be early entry for DCA, but again, you can hop back and forth all day as needed.
Have a great trip.