I have now read the other post, and I think you should take the advice given there: Get a smaller boat. You need one that you can right by yourself if it capsizes. Even if you have both your wife and son on the boat, your wife will be in the water helping the child, and will not be assisting you in righting the boat.

While your children are young and until your wife is experienced as crew, I would recommend the Hobie Wave. It is very stable, the least likely to capsize, and the easiest to right. It can handle a lot of weight. It has more seating area than either the Hobie 16 or Hobie 18. It cannot "turtle," because of the masthead float. (This is VERY important when you have small children on the boat.)

You can get the jib option for it and also the single-trapeze option -- that way there is something for everyone to do; your wife can handle the jib, and your son can have fun on the trapeze. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> They have a small spinnaker option for the Wave, too.

I forgot to mention that it only takes a few minutes to put up the mast and the sail and be ready to put it in the water. And if you have beach wheels, it is very easy to launch and take out of the water (especially if you have the bow spreader bar, which I highly recommend, and you can get that separately or it comes automatically, I think, if you get either the jib or spinnaker option.)