First, relax. Plan to have fun. The biggest difference in the 7 day is the formal night. You can use the same outfit for formal and semi formal or bring 2...your choice.
You haven't given us a lot of info about you or your family. Little kids who spill on clothes? Pack more kid clothes. I usually plan on 4 "bottoms" and 5-6 tops per person, and a couple of casual dresses that can be for normal dinners or worn during the day.
Shoes are a pain as they take up a lot of space. I use black sandles with formals and during the day. I wouldn't wear these comfy shoes with a formal at home, but it looks ok and saves bringing a pair of dress heels. My thought is sandles, pool/beach shoes, and wear my sneakers when I board. I will use the fitness center, so want sneaks. That way, I've packed the smaller shoes.
We always bring way more than we need. Remember that there is laundry available--do it yourself or send it out. I'm not saying that you need to PLAN on laundry, but if you hit an unexpected need, it's there. We pack what we think we'll need, but no extra. I figure that if we need the "extra," it can be handled with a single load of laundry. When we do WDW first, I do laundry there on the last night, so I start with everything clean on the cruise.
Bring 2 swimsuits per person (I hate putting on a wet suit). There's a huge packing list on this site, but really, much of it is stuff that I don't need and don't bring. One help is a shoe keeper that hangs on the bathroom door. It holds all sorts of stuff--sunscreen, deodorant, shampoo, etc. All the stuff that needs a home. I plan to bring sunscreen, tylenol, etc--you can buy that stuff on board if needed, but it's costly.
I have a fold up suitcase that collapses to very tiny. I put it in our big case and use it as a dirty clothes bag. That way, when I get home I can drop it in the laundry room and deal with it the next day. The bigger case then has room for whatever we buy, our CC towel, etc.
Also, when doing WDW first, I pack a "cruise only" bag of stuff that I know I won't need until the cruise--formals, etc. It doesn't get opened till we are on board. If you are flying, "mix" your suitcases. Put 1/2 of your clothes and 1/2 of husband's clothes in one suitcase. That way, if the airline loses your luggage, you still have some clothes to start the cruise!
