It really all depends. We have annual passes, so for us, it doesn't matter how many days we spend in each park. In August, we chill by the pool for most of the day and do a park in the evening, then set one or two full days for AK. We have premium annuals, so we do both water parks, Blizzard Beach usually twice and Typhoon Lagoon for a half day unless we've got friends with us. If we do a quick June trip, we usually spend the day by the pool in the morning, we do MK and Epcot in the evenings, and we set aside one day for Animal Kingdom. Except for the year Star Tours reopened; it would have been awful to not do that while we were there.
In January, I'm going with a friend, so our schedule is:
Day 1: Arrive, check in (approx. 12 pm) head to DHS. Once we get sick of it, go to Epcot (walking distance, boat, or bus, depending on what end of the park we want to get to).
Day 2: All day MK UNLESS it is too crowded. If so, we'll head to Epcot for the evening. But Splash Mountain is only open for the first weekend, so we're trying to get on it
Day 3: AK until closing, dinner at Boma's, MK EMH
Day 4: DHS, see Fantasmic at 7, late dinner and EMH at Epcot
Day 5: All day MK (We got a BOG reservation!!!!)
Day 6: Haven't decided yet what to do during the day (we're thinking Epcot or Disneyquest), but we have dinner at Teppan Edo
Day 7: DHS backup Fantasmic! day (I always recommend this in case something weird happens, like the weather turns or the dragon doesn't come out...) we're thinking of doing Splitsville after closing
Day 8: Haven't decided, but reservations for Chefs de France that evening
Day 9: Last day, pick up time is 5:45 PM for airport, so we might do Disneyquest or Animal Kingdom
And that is how you do the college girls' trip. Obviously, your group is not two nutsy college girls, but you get some of my general ideas, meaning:
-Always get a park hopper ticket
-Food is better over at Epcot, so a lot of times we'll hop over there. Epcot is also good in the evening if you've spent the day at Animal Kingdom.
-Are you staying at a Disney resort? If so, definitely take advantage of EMH. You might prefer mornings (I'm not a morning person). If you are not
-Leave days open so if there is a park you want to hit again, you can.
-Make reservations ASAP. You can always cancel or rearrange (unless you are fortunate and get a BOG reservation, in which case DO NOT CANCEL IT!)
-I don't know how your kids will be about going and going and going...you may want a day where you chill.
Have fun and tag me or reply to this if you'd like more info