You cannot over dress on a Celebrity cruise which I am sure you will really enjoy and it is a really good choice for a first cruise, if you want a good standard. They have three dress codes - formal about three times, which for men means DJ or lounge suit, - smart, about five times which means shirt and jacket - casual about five times which means smart casual shirt and slacks but not jeans or shorts. Just use good common sense and you will really enjoy it and do not worry about it as you will soon get the hang of things.
Celebrity is a 5* cruise line. You will find that the great majority of passengers are well-heeled Americans. They will dress up on formal night and the dress code is enforced. 12n cruise has 3 formal nights.
Go on the Celebrity website FAQ and look for clothes , packing or what to take questions. We are also going on Summit in August, and I'm trying to be creative with hand luggage etc!! We've only cruised from England before - with no weight restrictions. I'm looking forward to it though, have fun.
Another plus point I think! I hear that Summit has had a face-lift, with the rendevous lounge area getting a stretch. new-type engines fitted also, which is good news as they were dogged in the past by bearings failures.