For me, the answer is easy. My wife and I live in Huntington Beach, and with two small children, we don't get out as much as we once did.
Captain Jack's in Sunset Beach is a real gem. It's funny, in that it looks awful from the outside, almost like a dive bar. But if you ever are in need for a place to eat and find yourself on the coast in Long Beach, Newport, or Huntington, it's worth checking out for sure.
The place has a small bar and entrance, but you will feel at home and amongst friends on most nights. The crowd seems chummy and everyone seems to know each other, as the well heeled locals probably frequent this place often.
They are known for prime rib and crab legs. My recommendation: crab legs.
Great appetizer: Sauteed mushrooms with butter/wine sauce. It's great. Nice bread too, sourdough and squaw? Served very warm, it's great. Veterans of this restaurant will dunk the bread in the leftover butter/wine sauce, it's indescribable.
OK, so that's my favorite dinner place. What's yours, and why?