In the mini-suite, it's a tub with a low ceiling. DH is 6' and is cramped, but it works. The tub itself is a decent-sized tub.
In the suites, there's a seamless glass-enclosed shower and a separate jacuzzi tub. They are in the same section in the bathroom and it can be closed off from the toilet and sink area by a door. It's a walk-through kind of set-up. There's a door near the entrance to the cabin and a door at the other end just past the shower and close to the bathtub.
In the reg. balcony cabins and the outside cabins, it's a shower stall with a shower curtain that sticks to you. (thanks to SusanA for that info, BTW).
Not sure about the inside cabins, sorry.
Four people in a cabin is going to be tight. Good luck with it.