I haven't been to Tutto since 2010 (ignoring my recent stop at Gusto for a great new Tutto Italia dessert) or Mama Melrose since 2004 (so long ago!). So I don't have relevant firsthand experience with these restaurants.
We enjoyed our Les Chefs dinner very much in May, while Coral Reef has disappointed me twice for lunch (in 2010 and 2011).
For me, Coral Reef would be my choice to rule out - you can see the fish from inside the pavilion without using a meal credit there. Mama Melrose could be a good choice since you liked it before, and it's been getting even better reviews since the menu was updated. Tutto's post-refurbishment reviews have been less consistent, but I see items I think I would like on the menu (but don't want to pay OOP for, meaning they'd be a good value on the DxDP).
Good luck with the decision!