Here is my recommendation for your 6 full days (I have all dd's too):
AK - you can definately do in 1 day, but plan to be there the whole day if you want to see the parade & everything. I think your kids can handle it since it will close probably around 5pm in Oct.
MGM - you can definately do in 1 day as well. You can leave later in the day and catch the parade & Fantasmic.
MK - This is a somewhat slow time I would guess (except maybe for the days with
MNSSHP) so you should have no problem doing everything you want in 2 days (even with a mid day break). We like to split up the park & do Fantasyland, Toontown & Tomorrowland at one time & then do Liberty Square, Frontierland & Adventureland the next time. Be sure to catch Cindercellabration in front of the castle!
EPCOT - Definately a 2 day park. We made the mistake of not allowing enought time cuz I figured my kids would be bored & this turned out to be our favorite park! I think F&W festival will be going on too. Spend a half day or more at FW & 2 afternoon/evenings at WS. Your girls will love the kidcot stations as well as the shows. They are the perfect age!
Some other ideas:
Hayride, campfire sing-a-long with Chip & Dale & movie one evening at Fort Wilderness.
Chef Mickey is a fun character meal at the Contemporary & then you can ride the monorail (ask the CM if you can sit up front with the pilot!)
Since you have girls you should really consider a princess breakfast, either CRT or PSB.
Your girls will love getting character autographs, pin trading & penny presses.
Hope this helps your planning!