Wow, thanks everyone for all the responses! Lots of great tips. I will definitely look into pre-xmas timing. As far as getting that precious alone time with the 2 rooms -- unfortunately, doesn't usually work out that way for us on trips! I just know my 10-yr old will want to sleep with one of us in the room. So even if we had 2 rooms, it more than likely would be one parent/one child in each for the actual sleeping.
Also, I'll read the reviews on this site -- I didn't realize they were there. I remember hearing that most people don't like Carnival, so I was actually thinking Royal Caribbean was the way to go. Why is it that Carnival is unpopular? Is it because there are too many young children, or is the service poor, amenities sparce? Anyway, I will go thru the reviews.
Thanks again for all the help!
Mo