There is something about The Holidays. The decorations, the Christmas music, twinkling lights, brisk air, lots of traffic and pushy shoppers. :)
In all seriousness, though - I feel like photography can really come alive during Christmas time. I guess, that sense of wonder comes through in our Holiday casual portraits with the kids. Admittedly, I'm not the best at Portraiture but it all seems to just "work out for me" this time of year... Strange, no?
I think it really shows that your mentality can come through in the portraits you shoot. If you don't want to be there, it shows through in your work.
And this year, like every year, I really looked forward to our seasonal activity of unboxing Christmas lights and letting the kids play in them as we decorate the tree. This year, I put two Alien Bees at 45's in the living room. We shot some with strobes and some with natural light.
Some tips for others who might be looking to do this.
Turn on some fun or traditional Christmas music and try not to be too over-bearing on the kids. Let them play and capture the shots, don't worry with trying to over-impose your ideas on how they should be. Set the stage but find the shots, don't build them. This way, they are genuinely having fun (and it shows!) Do be careful that no one removes and a bulb and inserts a finger, tonque or any other body part into the business-end of a Christmas light socket. Holiday electrocution avoidance protocols should be in effect. :)
This year, we switched to LED lights. Photographer's warning: LED Lights are actually pulsing. They have a refresh rate similar to an old computer monitor, so consider that when setting your shutter speed. It is quite easy to get the perfect shot but appear the LED is off.
Resist the urge to over-light holiday shots. Get just as much light as you need to keep camera noise at Bay but don't worry about trying to shoot as ISO 100 for clarity. Shadows and tones are great for holiday shots. (For these, we used the modeling lamps on Alien Bees but I seldom let them fire and even then only at low-power since they washed out the Christmas lights. In this case, I thought the reflection and glow of the lights was far more important than getting the perfect exposure.)
Bokeh (blurry background) is really popular for holiday shots, especially lights. Remember, you don't have to have a crazy-expensive lens with a huge aperture to get good bokeh. If you shoot your larger aperture (smallest f-number) and put lights sufficiently behind your subject and use your zoom (if you have it), those lights will start to bokeh-ify quite nicely.
Some locations and elements that work well for Christmas shots: Christmas tree farms, trains, city light displays, fireplaces, decorative staircases, the beach (think: sand-based snowman and festive santa-on-vacation theming), candle-lit areas, ice skating, anything with Christmas lights, manger scenes, even to simple things like your living room coffee table with milk and cookies and kids in pajamas.
The final tip I have is... Be cool. Parents seem to have lots of pressure to get just the right Christmas Card image. If you are stressing it, your kids will be annoyed or stressed and it will show through. If you have to yell at them "Look like you're having a good time, damnit!" then you probably missed the opportunity. Take a break, have some egg nog (I recommend Myer's Dark Rum).
Stay calm, have fun and if it doesn't work out -- just do it over another day.
Good luck to you and yours for your Holiday memory capturing! :)