Hi Shelley! Planning your park schedule in advance is a great way to ensure you'll have a relaxing vacation!
Extra Magic Hours are a fantastic perk for Disney resort guests. During these early morning or evening hours reserved just for Disney resort guests, the lines are generally short so you can experience lots of attractions with little waiting. If you are certain that your family will actually set the alarm clock and get to the park in time for the start of the early Extra Magic Hour or will definitely stay late in the park to take advantage of the late-night hours, then I would recommend you visit the park hosting Extra Magic Hours each day. If, however, you're not sure that you'll get everyone up and to the park before it opens or you have small kids who can't stay awake for the evening Extra Magic Hours, then you should plan to avoid the park hosting Extra Magic Hours each day since it tends to be more crowded during the main part of the day when you'd be there. Unofficial websites like TouringPlans.com and EasyWDW.com post Crowd Calendars that predict the best park to visit each day based on factors like historical attendance patterns, Extra Magic Hours, and special events. If my family isn't taking advantage of Extra Magic Hours, I usually use those calendars and visit the park expected to be the least crowded.
Of course, if you have the Park Hopper option on your park tickets, you aren't tied to visiting only one park per day. You could take advantage of Extra Magic Hours in one park in the morning and then have dinner in a different park that night.
Come visit us again at the Moms Panel if you have more questions! We'd love to help!