Group of 10 for dinner in Lower Westchester
Dolores is right, getting the reservation may be the problem, but doesn't hurt to try....
Blu or Harvest on Hudson - both in Hastings
Il Sorriso or Red Hat - both in Irvington....Red Hat just recently relocated down by the river and from what I understand it is bigger then what it was.
MacMeenamin's in New Rochelle
Graziella's or Laguna or Morton's Steakhouse or Noda's (Japanese Habachi, you could get your own table) or Zanaro's in White Plains.
Angelina's in Tuchahoe has a downstairs area that would accomodate you