Although I cannot speak for Concourse, as that I have never eaten there, I will say for Le Cellier that I do not think that my Hubby and I would be able to split a meal there.
While the serving sizes are substantional they are, in my opinion, not large enough for two people to share one appitizer, one entree, and one dessert.
I would suggest getting your own appitizer and perhaps sharing the entree and dessert. I think this would work especially if you are on the DDP, which I am assuming you are on.
I shared with my 2 year old steak lover and it was fine but there is no way two adults could share unless you went out of your way to order the biggest entree and appetizer. I had a cup of the cheese soup as an appetizer and a filet as my main course.