I think most cruiselines do have adjoining cabins. Depending on the category you choose, it is probably more cost effective to do that than get a suite. I've never seen a regular cabin hold more than 4 people.
I would check out the suite prices and then the cabins together. Remember, when booking two cabins, you pay full amount for the first 2 people in each, then you get the discounted 3/4 person price, so keep that in mind when checking prices of 2 cabins over a suite.
most cruise ships have family staterooms or family suites, this would be something to look into, there are very few on the ship so you need to book early. Donna gave you some very good advise regarding the pricing issue, for us a family of 4 it was cheaper to book a mini-suite than it was to get two cabins.