Encino for large group
Alcazar on Ventura between Louise and Balboa for Lebanese is perfect for a large group. The dining room is huge (and there's also an outdoor patio). You can order a bunch of mezza -- the Lebanese equivalent of tapas -- to share. It also fits the more casual variety, but is definitely a sit-down place.
Sisley might be a very good idea w/ that back room (I like the grilled veggie appetizer and chopped salad w/ eggplant).
Maybe consider going over to Sherman Oaks to Stanley's.
Cafe Cordiale in Sherman Oaks can easily accomodate and has a pretty wide menu.
Marmalade has a back room that can seat you.
Tempo and Rio could both work.
Yamato would be good if you'd like to take up an entire teppanyaki table.
I know it's a chain, but we had our office xmas party at Buca Di beppo in Encino.
We reserved the 'Pope table' which I believe sits about 15 people. It was like a private room with the pope's head in a lucite box in the center of the table. The meal was served family style and unlike Maggiano's, you can pick as little or as much as you want. I was very impressed with the service and the food ranged from acceptable to good. Everyone in our party enjoyed the atmosphere and the food.