My 2 teens want to go the Ivy for obvious reasons. I'd rather not spend over $200 on lunch for the four of us. Can we get away with a 2pm reservation for coffee and dessert without being banished?

Call the Ivy and ask them what time would be appropriate for the four of you to come for dessert and coffee. You will get the best answer that way. Make it clear when you make your reservation that it is for dessert and coffee, not for lunch.

You can go to the Newsroom for lunch across the street and then sit on the steps outside and see if anyone drives up. Most of the stars that go to the Ivy regularly are not recognizable--producers, etc....

If you see a bunch of paparrazi jumping out of cars with cameras in their hands, then take a look. Your girls will get bored quickly and move on.

Well, but then there was the day we were having lunch and both Barbra AND Liza arrived (no, not together). Even the usually unshakable staff seemed flustered.

I agree Alisa... we walked back and forth for over an hour and then stood next to a handicap elevator across the street for 30 minutes and could not recognize anyone.
My friend actually ate lunch and had 3 celebrities sit near her in a 60 minute period. I can't recall who she said...
You may be better off at the Starbucks down the street, on the corner. We've seen a few there.
Day of the week and time of the day seems to be a factor too.
A girl at Starbucks said that between 9am and 11am was a good time to spot celebs as they head to meetings or the gym.
Many people on this board do not understand, but having traveled with my daughter (+ her friends) to LA many times, I totally understand how thrilling is was for them to see someone famous.
Have fun... good luck!