She would love the trip! Don't even consider going without her! Even though I am considering going back to a monohull from a cat the cat is a perfect vehicle for what you have in mind! The only thing I would do is get a cat with walk around rather then bridge deck berths. You will have a incredible family trip. You might get a bit is sticker shock on the price of a large cat over Christmas but it will be worth every penny!
I would also take the BVI over the Abacos. It can be very chilly there in Dec if you catch a cold front. The BVI is a overall very calm charter ground. With planning even if you get a Christmas wind you can do fine. You will also spend more time at anchor and less time underway in the BVI.
George