We just about always book B2B sailings separately. The trade-off for us is that we almost always have to change cabins on the turn-over days. Further complication is that when we bid to upgrade and it is approved, in our considerable experience, it is always just for 1 of the legs so have to change cabins and usually floors and/or sides of the ship. No biggee for us as we always book some kind of shore excursion on turn-around days, pack our "stacks" and drawer items in our suitcases the night before and leave suitcases in the closet area, then all our hanging clothes are transferred to our new cabin while we are on tour. The double perks are definitely worth it for us and more times than not, booking as two (or more) separate sailings costs LESS.