Garden Grill is not vegetarian (and I am vegetarian!). I think they will accommodate vegetarians, though, if you have some in your party. The only reason I would hesitate on that one is because of the reports that it hasn't been rotating for months.
Of the ones you listed, we've eaten at Le Cellier, Les Chefs and Rose and Crown.
Of those, I am not in a hurry to go back to Les Chefs. It is such a pretty place, but it was just ok.
Le Cellier was very good, but it is VERY small, and tables are VERY close together. The whole thing felt kind of romantic to me. I think with young kids, it would not be ideal. Maybe I'm projecting my own worries, but I would be worried about the kids' behavior, whether they were bothering others, etc. I would rather go someplace where my worries would be less, so I could have a good time.
We quite liked Rose and Crown, and were able to view the fireworks after dinner. It is also small inside, but more laid back - a little more of a pub feel.
We have never been to Marrakesh, because I've read so many bad reviews of it.
Of the other suggestions in the thread, I've never been to Biergarten, but I have always wanted to, and it sounds like a good choice!