What sort of budget are you looking at?
At this age, you can do digital cameras, MP3 player, i-pod touch. And if they already have an ipod/ipod touch, itunes gift cards are a hit.
My son's a couple years younger but plays with the older boys in our court and these things seem to be a hit: A huffy green machine, scooters, basketball hoop, most outdoor toys (tetherball, balls) legos, nerf guns.
Also, you can do clothes, but listen to what they're requesting. It seems like this is the age that they really start recognizing brand names and developing their own style. Maybe they want a certain brand of shoes that you normally wouldn't spend the money on or an sports jersey and Christmas is the perfect time for that special purchase.
ETA: I see you're doing Disney a month after Christmas. You can also do a Disney gift card for each child, or purchase a few pins or vinylmations for them to trade in the park. Also, maybe you can suprise them with something special to do at Disney. Maybe the fireworks cruise, the dessert fireworks viewing, or even one of the tours at Disney or fishing cruises.