Life is short. Things happen. Go the entire time. You never know for certain when you'll be back.
With that said, we've been going every year for Christmas. There is so much more than you'd expect, which is why I'd advocate for an entire week.
BUT I also read that you've been going a lot this year, so maybe 5 days is enough. I'd almost plan one half day around seeing all the resorts. Things I'd recommend doing
outside the parks:
- Resort hop. Plan some time to ride the monorail and see the Magic Kingdom resorts. Contemporary always has a display, even if it is a tad bit underwhelming; Poly doesn't decorate much, but we always stop there; GF is the 'grand finale. Also take some time to go to the Wilderness Lodge. It's probably the best-decorated resort on property. If it's nice outside, book a carriage ride around Fort Wilderness. Some of the campers decorate better than Disney!
Then, plan a day where you go to the Epcot-area resorts. Do Boardwalk, Beach Club, Yacht Club, Swan and Dolphin. BW used to have a more extravagant display... it's still nice, though. Beach Club is AWESOME. It has a working carousel made of gingerbread. Yacht Club has a stuffier feel, but it's beautiful during the holidays. Swan (I think) has a towering Christmas tree made from white poinsettias. The palm trees lining the path between the two resorts are lit in red and green and "dance" to Christmas music. It's like the Osborne Lights Lite(c) ... very lite.
Animal Kingdom Lodge is beautiful, too. It's 1A to the Wilderness Lodge.
- Do Disney Springs. I know, I know - it's an "outdoor mall"... but it's fun. We like to window shop and Disney Springs should brign back the Christmas Tree Trail. It's
okay. Wouldn't go out of my way, but if you're there...
Inside the parks is even more... Unlike Halloween, Christmas expands well beyond the party and the park.
- In MK you need to do Jingle Cruise and grab photos of the castle all lit up.
- DHS has new holiday offerings and Jingle Bell Jingle BAM was vastly improved this past year
- Epcot has a holiday festival and the Candlelight Processional
Not to mention, you have the regular park activities and new lands to see (depending on the last time you went)..
What I'd do:
Day 1: You're getting in late. Skip this day and relax at the resort. Go to Disney Springs that night
- Dinner at Disney Springs
- Christmas Tree Trail/shopping
Day 2:
- Magic Kingdom Resorts: Wilderness Lodge, Contemporary, Poly, GF
-
MVMCP
Day 3: Go to Hollywood Studios
- See the new TSL: FP+ for Slinky, ToT, RnR
- Check out the Sunset Season Greetings
- Jingle Bell, Jingle BAM
Day 3:
- Lunch/Dinner at Disney Springs
- Christmas Tree Trail/shopping
- Disney After Hours
Day 4:
- Epcot: book a Candlelight Processional meal if available
- Go to the Epcot area and check out BC, YC, BW, and Swan and Dolphin
- Return for Illuminations