Hi sweetsheila, welcome to Cruise-Chat. Every Princess ship we've been on has been great. They're all immaculate, the staff have been wonderful, and the food has been great. We've never been disappointed in any of our Princess cruises. The Sea Princess is my favorite ship, she's just the right size, not to big but big enough. The Emerald is beautiful, but huge. Which itineraries are you considering? The formal nights on board Princess are not ship dependent, they are determined by the length of the cruise. On formal nights, if you dine in the dining room, your hubby will have to wear a jacket. You can, however, dine in the buffet area or one of the specialty dining areas and not have to worry about the dress code for the evening. And, many go back to their cabins after dinner and change into casual clothes.
I think whichever ship you select, you'll not be disappointed.