There are two trails to avoid at all costs, for reasons of chronic iciness. White Nitro and Spillway are both unnecessarily wide, with extremely hard artificial snow. Man-Made snow on supersteep pitches like these tends to get scraped off with lightening quickness.
A few trails that are must skis if the snow is fresh are Bubblecuffer, Winter's Way and Powder Keg. Powder Keg is a snowfield run so it might not be open that early, but it does tend to fill up with snow very quickly compared to some other snowfield runs. Winter's Way is never groomed and is always on natural cover, with a good steep headwall and a big S-turn that gives the trail a good bit of character. Bubblecuffer is one of the oldest runs on the mountain, and possibly the best. It's headwall is a good 45° with narrow S-turns for it's whole length. Watch out for Hummer sized boulders and Volkswagen sized bumps though, or you'll get your bubble cuffed. lol
Like KevinF said, Narrow Gauge is an awesome speedball run. It is one of only two licensed F.I.S. Downhill Courses in NE (The other is "F.I.S." at Sugarbush), and has a good headwall about a third of the way down. It's one of the few runs in NE where the ski patrol ignores speedball skiing (some Others are "Dipper" at Burke, "Profile" at Cannon, and "F.I.S" at Sugarbush).
A trail I'm not too keen on is Skidder. They claim that it's the steepest mogul run in the east (which it definately is not), and as such it attracts a lot of people who really shouldn't be on it. They traverse and sideslip down, making the moguls really choppy and uneven. A much better mogul run is Haulback over on the King Pine lift.
since you're staying up there for a few days, check out Saddleback one day. It's about 15 miles west of Sugarloaf in the Town of Rangeley. It gets about 100" more snow per year, and is completely deserted. If sugarloaf is getting skied off by the christmas crowds you can find much fresher snow at saddleback. Saddleback also has snowfields, which fill in much faster than those at Sugarloaf, but you have to scramble up a couple hundred feet to reach them. (It's worth it)
Have fun up there.