LA area suggestions (I have not been to either of the 1st two, but legendary status propagates northwards):
Lawry's Prime Rib, Beverly Hills...
Fogo de Chao, home of the "meatsicle":
Or, Fleming's steakhouses in Woodland Hills, El Segundo or Newport Beach (there's one out in Rancho Cucamonga too...) At least some locations offer 'private dining' with rooms of 30-60 seats but I expect with Calgunner ingenuity we can pack more in a room. Expect, without wine, a prix fixe
dinner of salad + meat/side + dessert to run at least $60-$70/head.
I can testify that the one in Palo Alto is scrumptious.