The parade: DL is getting a new parade so maybe WDW can steal some of their ideas for the future. They're getting a New Orleans shadow man voodoo style section, and a Nightmare Before Christmas seciont.
I think WDW's parade could swap out some scenes. I realize that the Boo to You parade is meant to incorporate most lands in MK: Main Street is the Mickey and friends section, Adventureland is pirates, Frontierland is Clara Cluck and the square dancers, Liberty Square is the HM section and then there is villains. I feel that the Frontierland section should definitely be swapped out for a Hocus Pocus or Nightmare before Christmas section, the parade already leaves out Tomorrowland so taking out the Frontierland section wouldn't destroy it.
Decorations Beyond Main Street: yes please. I think DL does this best with Christmas. A lot of the lands have Christmas decorations themed to that specific area, like Carsland cars themed Christmas and Critter Country has very rustic Christmas decorations.
They could do up Liberty Square with a lot of cornstalks and harvest themed decorations, Adventureland could go heavy on the voodoo type inspiration, Tomorrowland could have metal pumpkins.