You are making plans to visit Walt Disney world, do you really need to think about what park on what day to visit? Yes to have the best experience. I hate to wait in long lines, if I can avoid it by doing a little research all the better. So how do I pick out which park on which day? I do the opposite of what other people do!
Many people look at the extra magic hours and decide they want to stay out at Magic kingdom until midnight so that is the park they want to visit to get their moneys worth. I think about all the people who are going to magic kingdom that day and head to someplace else! And some look at the Disney park schedule and see a Christmas party listed so they don’t want a shortened day and they go to another park. I look at the Christmas party as my ticket to lower crowds, we ride all we want at Magic Kingdom until 6pm. Then we head out for dinner and a relaxing night in the pool.
Here is a link to the Disney park hours: https://disneyworld.disney.go.com/calendars/2014-07-18/
And I use Undercover Tourist to get an idea of park crowds by day and parks to avoid: http://www.undercovertourist.com/planning/when-to-visit/disney-world-crowds-calendar_may-2014.html#disney-opening-hours
IF you really want to go to the Magic Kingdom on a Monday will you have a horrible time? NO, but if you can go on a Tuesday you will more likely have shorter lines to wait in. If you are traveling in mid-October it matters less than if you are visiting in mid-July. So if you have some flexibility look at the calendars and adjust your park plans based on anticipated crowd levels.