shana, on our last two cruises, which were both 15 days, they served lobster twice in the main dining rooms. They served shrimp twice also, but one of those times was with the lobster. The other time was with filet mignon, or "Surf & Turf", as they call it.
They also had beautiful large shrimp twice in the Horizon Court for buffet lunch (and not the same days it was served for dinner).
Lobster is also one of the entrees available every night in Sabatini's; Sabatini's will spoil you beyond repair. We didn't try Sterling's Steakhouse, but I would imagine the have a steak and shrimp or lobster combo. Hopefully someone else knows for sure. Both restaurants have a cover charge.
Wow! I have this sudden craving for seafood.