Where to start....Pontoons especially modern version are great sure but there is no wind break on them or at least not until you get into the lower 6 figure models. You are exposed to the wind all day long and can't get behind the windshield, close the center window and bow door to get away when you've just had enough.
For your family, what you have going for you is that the kids are still small....but they will grow and it happens fast. Adding on another family of 4....with fishing going on....you are going to need at least a 24 foot bowrider and I think in reality larger for a comfortable day and then you will need a 5.7 or a 6.2 versus the base 5.0 that may come in some of the 24 footers. I've got two boys they were little when we bought our previous boat (actually one wasn't born yet) which was 18 feet and as they grew needed something larger and so moved up to our current which is 23'9". It's just about right for our family of 4. I can't imagine loading up nine people on there for anything other than a cruise and get ready for hooks in you seats if you plan to fish with little kids or even inexperienced adults. We don't fish out of our main bowrider because they don't make good fishing boats for a whole host of reasons.
For your family, what you have going for you is that the kids are still small....but they will grow and it happens fast. Adding on another family of 4....with fishing going on....you are going to need at least a 24 foot bowrider and I think in reality larger for a comfortable day and then you will need a 5.7 or a 6.2 versus the base 5.0 that may come in some of the 24 footers. I've got two boys they were little when we bought our previous boat (actually one wasn't born yet) which was 18 feet and as they grew needed something larger and so moved up to our current which is 23'9". It's just about right for our family of 4. I can't imagine loading up nine people on there for anything other than a cruise and get ready for hooks in you seats if you plan to fish with little kids or even inexperienced adults. We don't fish out of our main bowrider because they don't make good fishing boats for a whole host of reasons.