It is obviously the busiest time of the year, and there isn't much you can do to avoid crowds. The good news is that The Canyons moved the gondola at the base to funnel in the skiers coming from the parking lot (Cabriolet lift), and installed that orange bubble thing you can see on the website. This means any lines on the bottom of the mountain are non-existent or mostly gone during normal times, and shouldn't be too bad around that Christmas to New Year's time frame.
The central part of the mountain will be crowded, but as intermediates you can easily ski any of the eight mountains there except 9990. During this one week of crowds, get the heck away from the Red Pine area and go to either side of the resort. You will have great intermediate terrain and will likely miss the lift lines.
The weather? It usually isn't too cold there but like anywhere else you have to plan for anything.
BTW, I can rent you a slope side/mountain view condo (sleeps 6) between Dec. 27-30 only (no New Years). PM if interested.
The kids (any age) and you will like the Olympic Park and museum.
I cut and pasted this from another post to help the kids find fun stuff to ski:
Fun runs at the Canyons Resort:
1) 9990 Lift: Ski the entire mountain. Single and double diamond only. The Fright Gully trail is exactly that. You motor along until you hit this really narrow and steep little pitch, hence the name. On powder days remember there was a deadly avalanche there in bounds off to the side. They are very careful about blasting it now . It will open later on powder days.
2) Off Tombstone Express Lift: Grande into Pinball Alley (natural half pipe). Go straight off the lift for 20 yards or so and access Grande through the fence (small opening) on the right. Grande starts relatively flat, makes you almost walk through some tress until you get to a steep wide open “field.” Stay as far left as you can so you will be dropped into Pinball Alley, a fun natural half pipe. Then it is flat back into Red Pine.
3) Dreamcatcher Lift: Phantasm Woods (you will see it if you bear to the far left off Pipe Dream) is killer on powder days, as is the entrances to it off Chimera.
4) Dreamscape Lift: Never a line there (like Dreamcatcher). The runs are listed as “Blue” but are closer to black elsewhere with moguls. Decent runs, few if any people on them, and a flat boring cruiser back to the lift.
5) Saddleback Lift: Most tourists hang near Red Pine Lodge not wanting to venture around all the mountains. Just go off to the right and ski The Pines. Go through 10 yards of the trees at the lift and you can ski Ecstasy. At the bottom you can run into another half pipe (not difficult, but fun). Ecstasy, Gallery etc. are all great on powder days when other lifts are closed for avy control. This lift will be crowded over Christmas-New Years, filled with first timers to the resort and the ski school.
6) Shortcut Lift: Most people ski Doc’s Run to get off the mountain, unless they wimp out and take the gondola. Once you are on the mountain Shortcut will take you to Doc's. For some unknown reason, there are few skiers ever on the runs next to Doc's: G-Force, Super Fury, Silverado Bowl, etc. Nice runs not hit first by the best skiers on powder days.
7) Sun Peak Express: I like Mine Shaft. Coldest part of the resort.
8) Super Condor Express: On a powder day, check out everything to the left (West Boundry to Yard Sale) while you are going up the lift. When 9990 is delayed for avy control, these runs are the nuts. After it snows, Murdock Bowl is usually closed for blasting (you have to hike to the top) as is BOA, the cruiser just below it. If you go down BOA check out the Canis Lupus half-pipe to your right. They run a race on it at the end of the year. Insane. You can also get there through Condor Woods (tree skiing).