The Shuja Yacht runs a Saturday brunch, I haven't been, but really want to go myself, there was an article in Time Out Abu Dhabi on brunches, it's 215 per person including bubbly, leaves from the dock near Marina Mall. I think you book it through Le Royal Meridien.
That would be a pretty special memory for guests, brunch and cruising on a yacht!
If you opt for this be sure to let us know how it is!
Might also be worth checking out Time Out for some other ideas.