celebratory dinner for 12 in the east bay
Given that you've specified no parameters on noise, style, or what 'pricey' is, I'd recommend the front table at Cesar on Piedmont.
Or one of the big tables at China Village - I've taken mixed groups there with great success - they do a good job with the less adventurous chinese food too, like (OMG!) lemon chicken.
I'd second Cesar or Pizzaiolo, and add:
Luka's (the large table near the door will work for 12 (but no more). Excellent bar (though not quite as good as Cesar). Food includes cheese and charcuterie, excellent fries, nice soups, steak, mac & cheese, a good burger...something for everyone. The atmosphere is fun, but loud. This place attracts a real cross section of Oakland. Business people, hipsters, families w/ kids...