I think you still have quite a few options available for this.
I've flown both non stop and connecting from the two airports in my area (Cleveland and Akron). Only once out of all my flights was my luggage "lost", and that was on my way home from Orlando with a connection time of 34 minutes at my layover (and thats why it was "lost").
Depending on when you're traveling, I'd tell you to check with Northwest, who still does non stop into Orlando. If you're booking flights outside of three months, make sure you pay with a credit card in case of bankrupcy, or book with a
travel agent that can offer insurance to cover this reason.
If Northwest's prices are high, or your afraid of them not flying, check into Airtran for a connecting flight. They have their layovers in Atlanta (I know, I can hear everyone complaining about Atlanta now, but I love this airport!) but Airtran only has about 16 gates there and they are all in one area. I would say if you had to walk from the two gates farthest apart it's about a 7 minute walk.
If you're looking at other airlines than these, just make sure your luggage is mixed up, so everyone has at least one outfit in anothers suitcase, and make sure your layover is around one hour long, or even longer to make sure they make their transfer.
My other suggestion would depend on your route of travel. If your staying onsite before your cruise, maybe consider shipping via UPS some of your clothes down to Disney. May cost you some money, but it's trackable.
I hope this helps some!