You can wear jeans and shorts in the dining room for breakfast and lunch, but you shouldn't for dinner. I have seen them turn people away from dinner who were wearing shorts, but I've also seen them allow jeans in during casual nights.
For breakfast and lunch, most people are very casual, even in the dining room, not just the grill or buffet. Most people do dress up more for dinner. For casual dinner, my wife usually wears dressy pants and a nice blouse; I wear dockers and an aloha shirt or polo style shirt. For informal (think semi-formal), she'll wear a pant suit, or a nice but not fancy dress; I'll usually wear a sport coat and tie, but sometimes I'll just wear a dress shirt under the sport coat, including turtle neck style dress shirts, and no tie (believe me, there are many men who are even more casual). For formal, she'll usually wear a formal dress or cocktail dress (most of which she's found on sale racks at the departments stores for less than $100, and some MUCH less than that); I usuall wear a tux that I bought on the internet for less than $125, including the shoes, and has lasted me for many cruises already), and last year on Century, I wore a dark suit.
We believe in dressing according to the dress code (and it does say "code" on the dailys), and it is a topic of much contraversy on the boards. But don't let any of the negative comments throw you off. You will meet very nice people on your cruise, and you'll see all kinds of variety regarding different degrees of "dressiness". We've not found it a hardship to find clothing that will work just fine.
Don't worry... go and have fun.
paul
