weather, skiing mid-week, MLK weekendWeather: It might not be so cold (i.e. might be around 30-35 degrees or more) so make sure to bring stuff to keep you dry and not too hot, i.e. a good 20000 shell/layers is preferable to an insulated jacket.
Squaw: Hit Squaw mid-week & you'll be doing laps. Seriously, just get up & head over there (should be no traffic around the lake). If you think you've skied everything there after a few hours - you haven't. Head to Silverado, be careful, & don't get cliffed out.
If you don't mind the drive, do it again & hit Alpine Meadows midweek.
Kirkwood: Hit the 'Wood on Saturday 1/13 & leave the crowds at Heavenly. It's MLK weekend.
Mt. Rose: Hit it on the 14th & go straight to the airport or stay in Reno & party that night before you fly home. Even if you've got a reservation in Heavenly for Sunday night, Reno lodging on a Sunday night is uber cheap & you'll appreciate having a 5 min. drive to the airport.
Heavenly: I don't have any special knowledge, but there's lots of good tree skiing, so long as you don't pull a Bono (Sonny, that is). There's also Mott/Killebrew & the Nevada side in general...