Cruising on today's modern ships no longer calls for dress-up clothes in the evening. You will not want to wear formal wear on land tours. What is appropriate at all times is what is called "resort casual."
By day, almost anything goes—shorts, jeans, skirts, etc.—even swimwear with a cover-up is okay in the Buffet. Nice jeans, collared shirts are great for guys at dinner. Slacks or jeans, dresses, skirts and tops are perfect for women. If you want to dress up a bit, that's up to you. You can be more formal in one of the "extra charge" restaurants, if you like.
No matter where you go, you may have some chilly evenings especially if you are near water. Take a sweater, windbreaker, or sweat shirts for those cooler days. If it rains while you are on shore, an umbrella and/or rainwear will come in handy.
Here are some of the items I have found useful:- head scarf for sightseeing in cathedrals
- jacket for rain showers
- hat with visor
- sweater
- travelers checks
- luggage locks (new ones okayed by airlines)
- really good walking shoes
- exercise clothes
- one credit card
- plastic bags in several sizes
- passport
- driver's license
- tote bag for snacks and your water
- business cards to pass out
- small flashlight
- card games
- ear plugs in case your roommates snores
- bathing suit and coverup
- beach shoes
- sunglasses
- travel alarm clock
- umbrella
- medication for two weeks
- camera with batteries
- film or memory card
- Handiwipes
- cell phone/laptop if you want to keep in touch