I've made many trips for 2 days of skiing, from the DC area to northern VT, NH, NY. 2 days at whiteface/Lake Placid - About 11 hrs each way. Have done that 2 or 3 times. I've also done the drive from DC to Cannon for 2 days of skiing (an exam). Then there was the drive to Wildcat for 2 days back in my sr year of high school (also an exam). I drive to Killington every year, but that's for week long event, and have driven to Jay for a week long trip. The most memorable drive was the trip to Wildcat, when I left the ski area at 5pm and drove all the way back to school in one shot after a full day of skiing/stress at an exam, by myself.
But my longest drive for skiing would be the 1700 mile trip from DC to Summit County CO. But I stayed there and got a job (as a ski instructor - so it was for the sole purpose of skiing). I did the drive in 2 days, at about 13 hours per day, by myself! (did the return trip in 2 days as well)
I almost forgot to mention... my longest drive for one day of skiing was a few early season trips to Hunter. About 6.5hrs. We'd leave in the evening, stay at a hotel about an hour short of Hunter, then ski the next day and start the drive home at about 5pm. Get home around midnight.