Have everyone in the party make a must do list.
Have everyone make a like to do list.
Compare the lists and come up with a grand list.
If your party has drastically different lists, consider splitting up. No reason for everyone to stand in line for Space Mountain when only two people want to ride it and everyone else can take another turn on Buzz Lightyear.
Don't be afraid to park hop. Most people like to do Epcot late - lots of places to have dinner, its open later most times.
Don't be afraid to make PS arrangments for dinner. Eating from counter service restaurants night after night WILL get old. And during July it can be hard to find someplace to eat - particularly inside MGM and Epcot (MK has few sit down places anyway - we don't do sit down there - besides, its so convienent to eat at one of the monorail hotels. And AK has almost no sit down either - but you will be out of their by dinnertime - they always close fairly early). (menus can be found at
www.wdwig.com).
Recognize that there is no way you are going to do it ALL on this trip - and relax and get the things done that are most important to you. Including spending some time laying around the pool.
Know the lay of the lands before you go. Any guidebook is useful (I like Birnbaums for the excellent full color maps and pictures - your girls would probably enjoy Birnbaums for kids, but the other guidebooks are better for getting the real scoop - so we buy two - every couple years, cause its the same old same old). And then review the maps the night before you hit the park. A large family standing around Tomorrowland with map in hand wondering where the Haunted Mansion is - not a pretty sight (although some helpful person will be happy to help you).
And yes, do a character breakfast - or lunch, or dinner, or ice cream social. Make PS for it though!