Might be too late for you but the Stevensville TH on the west side of Mt Mansfield makes for some nice loop hikes. A summit traverse involving the Maple Ridge and Sunset Ridge trails and the CCC Road makes about a 9 mile loop. Get a map and little imagination and you could easily make that longer. Perhaps add the subway or cliff trails, could be extra challenging if icy. 9 miles in winter conditions would in theory be slower going anyways. That was one of my favorite summer loops. Perhaps head for Nebraska Notch to expand the loop.
Not a loop, but climb Camel's Hump via Bamforth ridge this time of year would be a very challenging day out or 2 days. Potential for route finding, not sure it gets allot of traffic on that route in winter. It's about 13 miles out & back if I recall, (~4K elevation gain) you can expand that by making some loops around the summit area (see map).
Edited to add --> My apologies to GM Goat, I missed his post, looks like I regurgitated it. (seriously I did not see it until I got done typing the above and was proofing it). He is describing roughly the same Mansfield loop I am, you can start it from near Underhill SP or Stevensville. Being cheap, I always preferred to avoid the SP fees and crowds and started at Stevensville. That is no issue in winter, the SP is closed, you would park about a mile below it where the plows stop.
