The only outfits that provide rides in their duos in the NE US are
Ridge Soaring, Philadelphia Glider Council, and Adirondack Soaring.
Harris Hill has one that they use only for cross country training
within the club. The one registered in Massachusetts belongs to
a private syndicate.
Check on the SSA web page for how to contact various glider operations
in the US.
http://www.ssa.org
-- Matt