sjr - first of all - no stressin' about the dressin'! And that's an order lol.
Carnival is pretty laid back - that being said I love to dress up but I don't like to "overdress". Dh would look like a penguin in a tux so he opts for a navy blazer and gray slacks, white dress shirt and tie - and he looks fairly wonderful :o)
I always feel great in slinky pant suits or (as stated above) black silky pants and dressy tops. As for the cost - DH is Scottish - born and bred - need I say more tee-hee.
If it's a seven night cruise then you only have to dress up for two - but do it - the photos they take are great. We were really surprised how good looking we really are lol.
Have a great cruise!!