At WDW, the "not so scary Halloween party" occurs on many nights thru October, not just on Halloween. So, you could have the best of both worlds. You could do the parks before the cruise, then cruise over Halloween.
This evening at the Magic Kingdom does require an extra park ticket--a special ticket not part of annual passes or the normal park hoppers.
We love the 7 day cruise. The shorter cruises are just not long enough for us. But, in fairness, we've done both the parks and the cruises several times. Most fun really depends on what your family wants. The parks are a lot more work for the mom. The cruise is relaxing for me as well as fun for the family.
As to what category--this is totally a personal issue. You didn't give us any info on kid ages, etc. You can book a cat 12 gty. Technically, this only holds 3 people, which means that you will be automatically upgraded to an 11. This is an inside cabin with a single bathroom. If you will not be spending much time in your room except for sleeping and changing, it might be ok for you. On the other hand, if you need/want a place to "hang out" while a little one naps, or if you are into a romantic private breakfast on your verandah...well, you'd better have a verandah.
All the cabins are basically the same size in terms of living space. The differences are that cat. 10 - 5 have a "split" bathroom. THere is a sink and tub in one room, a toilet and sink in the other. This can be a big help in getting ready if you have a lot of people. Cat. 11 and 12 have the single bathroom. When you look up the square footage of the cabins, the measurements include the bathrooms and the verandahs. Cat 7 and better have the verandah., 8 and 9 have "porthole" windows. These are very large and let in a lot of light.
Really, only you can decide what cabin category you need for your family. Will your husband (or you) go to the fitness center every morning and shower in the locker room? Do you need to hang in the room while someone naps? (verandah is nice for this). How important is cost?
Another thing for you to look at (especially in the off season) is whether to book a land/sea vacation or whether to book them separately. You can sometimes save major $ by booking separately as WDW offers deals on resort rates. Also, you might choose a different resort level than is tied to your category on the ship (again, this can be a huge savings.) You might want a verandah on the ship, but be happy in the Pop Century on land. This can't be booked as a land/sea as each cabin category is tied to a particular resort category. THe only way to know for sure which is cheaper is to decide exactly what you want and price that. Then price the package. Finally, price the package items done separately. THen decide what you want to do.
If this is a first trip, get a good TA who has been to WDW (and preferably done the cruise.) You will benefit from someone who really knows their stuff the first time. However, do some pricing on the internet first so that you don't get gouged. Also, some TAs don't like to price things outside of the package (this is the easiest thing for them to do, not necessarily the cheapest.)
