Speak cruise and it'll bring me out of the woodwork everytime!
You all are going to have so much fun! Wish we could go with you all but we're doing the maiden voyage of the Dream in January... then we're going to rebook onboard for either the Alaskan or the maiden voyage of Disney's Fantasy in 2012...decisions, decisions!).
Here's a few tips pertaining to some of the posts above:
1) Don't watch the Poseidon Adventure or the remake, Poseidon, beforehand (loved that movie...but don't watch it!) Titanic is ok, no icebergs in the Bahamas
2) Deck 1 is your friend - all the
free meclizine (same as Bonine) you want.
3) Attend the Captain's Welcome Reception (free mixed drinks-alcoholic and non-alcoholic).EDIT: This is only on the 7-Night cruises....sorry about that 
4) Bring Nalgene Bottles to fill with the
filtered water on deck 9. No reason to purchase bottled water.
5) Stateroom coolers are just that...coolers and will keep cold things cold. Put a couple of Nalgene bottles filled with ice in the cooler to help. Your stateroom host will leave a card for you to check if you want ice delivered to your room each day (twice a day).
6) The monster toilet: Let young kids hear it beforehand so it doesn't scare the shi...uh...so it doesn't scare them to death. Sounds like it's equipped with a jet engine!
7) Decorate your door! Stock up on those peel-and-stick magnets. They don't allow you to tape anything to your door but magnets are fine.
8) Most importantly: Purchase the refillable beer mug. Refills are 3.75 (I think) for 22 ounces! Although the initial cost is about $14 for the first beer, you get a nice heavy all glass mug as a souvenir.
CASTAWAY CAY (the worlds best island!)
Buy the Getaway Rental Package for Castaway Cay. It includes snorkel gear, bikes, and floats. Get off the ship early. Snorkel as soon as you can that morning, the water is crystal clear before everybody stirs it up. And look for Mickey, Minnie, Donald's boat, and the old Submarine from WDW's 20,000 Leagues Under the Sea. I have locations for all these if you are interested.
Bike afterwards, the island is beautiful and make sure you go to the lookout tower. There's water stations on the bike routes. There are two routes, do them both and take your time. They don't hold you to the hour on the bike, we keep them for almost 2 hours and they said it's fine because they have plenty.
After stuffing yourself at Cookies BBQ, spend the rest of the time on the family beach floating and drinking
while the kids play. Or if you're adults only, chill on the Adults only beach
Get the full body floats not the tire-tube ones because they are not comfortable (but you can switch out if you don't like one or the other...they don't mind).
7) Geocache...there are a couple of caches on the island (so don't forget your GPSr). This is good if you rent the bikes.
NASSAU:
What we do - If you don't do Atlantis, I highly recommend the Pirate Museum if you have kids (but adults will like it too). DS was 6 when we visited it the first time and he insisted on reading every single trivia as you go. What should have been less than a 30 minute tour, ended up taking us about 2 hours at his reading pace! But it's fun, (educational
)cheap and within walking distance of the ship.
Do the straw market if you like to barter...love doing that! We also have done some land excursions and shopped some outlets for rum cakes, liquor (DH is a scouter for Patron tequila), tropical shirts, and hot sauce...oh hot sauce! If you are a connoisseur of hot sauces you must get some
"D'Vanya's Junkanoo Hot Pepper Sauce" it has the best flavor! I stock up on that stuff.
I have bunches of tips, just can't think of all of them right now, so if you have any questions, I'll try to watch this thread and answer them.
I don't get on here often anymore but a couple of my friends do...one told me you all were doing a Fort Fiends cruise so I couldn't resist posting
Just wish I could go too!
Didn't mean to write a novel here...but two of my favorite things in one thread....camping at the Fort and cruising with Mickey
...oops...the Dream is Admiral Donald, not Captain Mickey
but it's still Disney
)
I always tell my family they can't eat any in the parks because they'll be free in a few days when we get on the boat. 
