I have also heard to avoid the parks with early morning entry, at least for the morning portion of the day. You could park hop and then go to that park in the afternoon.
I did a little bit of research based on several popular WDW books at my library and this is what I discovered for the timeframe I was going:
Sunday - MK early admit, MGM busiest day, MK good day, Epcot good day, AK good day and Overall Least Busy Day.
Monday - AK early admit, AK busiest day, MK busiest day, MGM good day.
Tuesday - MGM early admit, Epcot busy day, AK Busiest day, and Overall Busiest Day.
Wednesday - Epcot early admit, MGM Busiest day, AK Busiest day, Epcot Busy day.
Thursday - MK early admit, MK busiest day, MGM busy.
Friday - AK early admit, Epcot busiest day, MK good day, MGM best day, Overall Least busy day.
Saturday - MGM early admit, MK busiest day, Epcot good day.
This may or may not be helpful but I am trying to use it as much as possible for my trip end of June.
Some of these seem to be conflicting but that is because they come from various sources (Disney website, AllEars.Net, Fodors ...)
I'm not sure if it is accurate, and obviously it can change with the whim of a million people, but I think it may just help a little bit.
