I haven't brought my ebags backpack to Disney for a weeklong trip, so I can't help there. I DID bring it to Disney for 4 nights and packed my stuff along with my son's clothes in it (we each also had one more small bag). I utilize the packing cubes and feel like that saves so much space. I bring things that fold compactly like a sundress that won't wrinkle, a running skirt and tank tops, one pair of shorts (I dislike shorts and only have one pair), simple PJ's, Croc flats, and wear my gym shoes on the plane. I tend to only bring just what I need, along with travel sized bottles of toiletries which could then be tossed once used up.
If you read the reviews to this bag (linked below), you will see what other people have packed in it.
We don't buy souvenirs except for pressed pennies, an ornament, a pin, and maybe one other small item. I am very realistic as to what I will actually enjoy when I come home (though I could buy out World of Disney when I am there, I know that I won't use/wear/need any of it once home).
Edit: Here is what I use to Pack:
TLS Mother Lode Weekender Convertible Junior Backpack:
http://www.ebags.com/product/ebags/...-convertible-junior/241465?productid=10209111
Pack-It_Flat toiletry bag:
http://www.ebags.com/product/ebags/pack-it-flat-toiletry-kit/54638?productid=949939
3 Piece Set of Packing Cubes (we all have our own color):
http://www.ebags.com/product/ebags/packing-cubes-3pc-set/13032?
productid=10150075
Slim Packing Cubes:
http://www.ebags.com/product/ebags/slim-packing-cubes-3pc-set/107842?productid=10467553
Padded Pounches (I put all chargers in here so they are organized and have a designated space so they aren't all over the room or tangled in suitcases):
http://www.ebags.com/product/ebags/...s+padded+pouches+-+3+pc+set&pl=hdr_srch_as_l1