By the way, OP, in my first post I suggested Rodeo Drive and Beverly Hills, as well as The Grove and Farmers Market up in L.A., for extra Christmas magic (though nowhere near as magical as DLR, but at night, still beautiful). I live about 3 minutes down the street from Farmers Market/The Grove in one direction (this is also the area where LACMA and the Tar Pits are located, is and pretty close to Sunset Blvd. and Hollywood Blvd.) and I'm about 4 minutes up the street from Beverly Hills in another direction. I can tell you that, on a day with
no traffic - or at least reasonable traffic - and depending on how fast you drive, you can get from DLR to my area of town in 40-45 minutes. Same thing on the way back to DLR from this area of town. But if you drive more slowly or if you run into traffic, it can double to 90 minutes or more.
The PP is right about the traffic during the holidays - it is crazy, especially right in the weeks leading up to and right after Christmas!
I don't know how long your trip to SoCal will be, but if you have lots of time, I can suggest other places to eat and things to do in general (not necessarily Christmasy) in L.A. or up this way, but if your time is very limited, I almost tend to think you should just stick with DLR and enjoy all there is to enjoy there.
I agree that the Long Beach area of town is nice, and the Queen Mary and Aquarium are great to visit if you have time. Also, Shoreline Village is a lovely little place to stroll around and eat lunch. Plus, Long Beach is home to the Catalina Express, which takes you over to Catalina Island - my 'other' favorite place to be in Southern California!!
As far as making dining reservations at DLR, while it is not as necessary as it is for WDW dining, you need to make reservations if you eat at the Blue Bayou - they require it there 99% of the time. It is not necessary to make reservations for the character meals, but it is highly recommended, as those can get very busy and the waits to be seated very long. I would also highly recommend making a reservation for Carnation Cafe - a lovely place to eat along Main Street with
very limited seating, and the wait for a table can be very long. Also, I would suggest making a reservation for ESPN Zone and Rainforest Cafe - I have waited for an hour to be seated at both of those places without a reservation.