We spend more like 1/2 day at AK (rope drop until about 1:30pm, concluding with a CS lunch -- this includes everything except the Bone Yard, Rafiki's Planet Watch and Kali River Rapids, and includes only one character M&G and one of the three live shows.) If you stayed until closing on a day with average-or-less crowds, you could easily do every last attraction in the entire park without breaking a sweat.
Epcot takes 1 1/2 days for us. After spending half a day at AK and going back to the resort for naps and swimming, we get to Epcot around 4pm and do most of Future World, including all the attractions, Club Cool and Character Spot (skipping only Ellen's Energy Adventure and the Innoventions buildings) by 8:30pm, with a TS dinner. The next day, we revisit our favorite attractions in Future World and browse the Innoventions buildings from rope drop until World Showcase opens at 11am. We then tour half of World Showcase (doing the Maelstrom, Mexican boat ride and American Adventure), have lunch, and go back to the resort for naps and swimming. We return that evening to tour the rest of World Showcase and have a relaxing TS dinner. On our way out of the park, we revisit the kids' favorite attractions (Mission: Space and Spaceship Earth) in Future World.
We could make Epcot a 2-day park if the kids had any interest in meandering through World Showcase. (They're only 5 and 7). It's the only part of Disney World for which they really don't care, although I expect they'll enjoy it more and more as they get older.
With 6 nights and 7 days, you can easily spend a day at AK and 2 at Epcot, leaving you another full day for HS and 3 days at MK. (Since AK tends to close early, your AK day is a good one to use for dinner shows, a particularly fancy sit-down dinner or a trip to Disney Springs, formerly Downtown Disney, to cap off the evening.) MK, beyond any question, holds the most interest for my entire family, with Epcot a close second. DH and I are indifferent to HS (Rock 'n' Rollercoaster and Tower of Terror are great, but motion sickness and height requirements disqualify everyone in the family but me), although our children really love the Disney, Jr. show, TSMM and Star Tours. Candidly, sometimes it feels to DH and I like we visit HS and AK mainly for "purposes of completeness" and not because we're thrilled by the attractions they offer.