I highly recommend taking a look at
HydroGuy's A DLR Guide for WDW Vets. It'll help give you a sense of the similarities and differences between the two resorts.
At this point, we're all still speculating a bit about what the schedule will look like for December in terms of the holiday offerings. DLR has said that A Christmas Fantasy Parade will be presented, along with both versions of WoC, but we don't know times yet.
Check out the
2015 Calendar of Events thread to get a sense of the events and activities that are happening while you are there.
Some of the bigger events that may impact crowds while you are there...
- Candlelight Processional (it's not as big as at WDW and it's not something DLR really promotes/announces) is happening on 12/5 and 12/6. It will impact crowds on Main Street.
- SoCal and SoCal Select AP blockouts start on 12/18, so there is usually a bump in crowds the weekend before as the AP holders come in one last time to see the holiday offerings until January.
- There are rumors that the Holiday parade/show taping may happen in December this year (12/11-13), but this is only a rumor. Still, it's something to keep in mind.
In terms of things not to miss (assuming 2015 is like 2014)...
- Attractions with holiday overlays (It's a Small World Holiday, Haunted Mansion Holiday, Jingle Cruise)
- Gingerbread House(s) in the GCH. They had a big one in the lobby (not big compared to ones in WDW, but still impressive), and smaller ones in Storytellers and White Water Snacks.
- Entertainment. A Christmas Fantasy Parade is cute. WoC has a holiday version (I found it a big Frozen-heavy last year, but we'll see if they've tweaked it this year). The streetmosphere performers (e.g., Dapper Dans, Five and Dime) usually have holiday songs in their rotation.
- Decor. The parks are usually really nicely decorated for the holiday. This year should be a mixture of the holidays and the 60th Anniversary.
- Viva Navidad is fun and worth checking out (Paradise Pier in DCA).
For dining, check out the
Disneyland Dining Review and Photos thread to see all of yummy stuff offered in DLR. There are usually seasonal offerings, which we'll know more about close to the actual holidays (right now, it's mostly Fall-offerings (lots of pumpkin)).