While there are 17 alpine skiing areas in Maine, the majority are small and only Sugarloaf, Sunday River and Saddleback have sufficient lifts and ski area to warrant an extended stay.
The thing about skiing in Maine is that all the resorts, with the exception of Bigrock perhaps, are within a reasonably compact area and are easily reached for a day visit if you're staying at one of the major resorts.
Sugarloaf is Maine's largest ski resort and has the only above-tree-line skiing in the east. With a snowmaking system covering 92 percent of the skiable area the resort is able to ensure sufficient high-quality snow on a consistent basis.
Bigrock Ski Area
Black Mountain Of Maine
Camden Snow Bowl
Lonesome Pine Trails
Powderhouse Hill Ski Area