I finished this 8' stitch & tape pram last year and learned a few things you might be able to use if you decide to go the build-it-yourself route.
First, I am happy I built a pram and not a pointy bowed boat. For a given capacity, prams are easier to build, easier to transport and easier to store, and a properly designed pram gives up nothing in performance.
Second for 2 adults and 2 kids you will need a boat bigger than 8'. For a pram I would say at least a nominal 10 footer and for a pointy bowed boat you are probably looking at a nominal 12 footer.
Third, while I am quite pleased with my stitch & tape dink, if I ever build another boat it will be glued lapstrake. Glued lapstrake requires more work up front cutting and hanging the extra planks but you come out ahead in the end because there is much less fairing and sanding required to get a good looking finish. Cutting and hanging planks is fun. Fairing and sanding, not so much. Also, most people find most glued lap boats to be more aesthetically pleasing than most stitch & tape boats.
To those points, I would add don't worry about a nesting dinghy as even a nesting dinghy is not going to fit comfortably on deck on a 22' boat.
In my opinion, the best 10' (nominal) glued lapstrake prams are Joel White's 9'6" Nutshell Pram (already mentioned above) and Ian Oughtred's 9'4" Granny Pram. These are both tried and true designs that have been home-built hundreds of times and you can't go wrong with either one.