Out of the 3 - Narcoossees! get a great view of Wishes, and I'd say it's more romantic than the others. However, I don't like Le Cellier so that sort of swayed my vote
Narcoosies - great seafood and atmosphere
Yachtman - we go EVERY SINGLE TRIP - fabulous service and atmosphere
LeCellier - fabulous but very crowded.
If you are already going to be in a park, then LeCellier, IF you can get in. It is one of the most popular restaurants now, very busy and quite small. You will have a great meal but it will be busy and noisy, not intimate.
Yachtsman and Narcoosies tend to have less children - not sure if that is a factor or not.
For a meal without kids I'd do Narcossee's. The food is delicious and the service is wonderful. Although I've seen kids there it has a more adults only feel.
Out of these 3, I'd choose Yachtsman. It's a bit more upscale, the food quality is higher and you have a slighty better chance of enjoying a quiet meal.