Circumnavigating is a wonderful and an achievable goal for many people PROVIDING that they understand and prepare for the many "challenges" of long-distance ocean sailing, and that they honestly assess their own skills and experience. Without knowing any more than you've revealed to us thus far, I'd say, "by all means, keep the goal of a circumnavigation in mind".
That said, I think the idea of setting forth on a circumnavigation without proper experience and equipment is just plain nuts. It's fine if you want to do this yourself, and put yourself at risk (though you may also inadvertently be putting other lives at risk among those who may have to rescue you). But to do this with children who don't have a say, and aren't able to make a choice, I think is the height of arrogance and stupidity.
Re: your adventuresome husband, every single day is an adventure when cruising. You don't have to cross an ocean to be adventurous.
Now, let's look at what's really doable. How about an intermediate goal of a few years of coastal and island-hopping cruising, with the kids, to gain experience and to prepare yourselves and your boat for the ultimate goal of a circumnavigation? Such a plan affords many opportunities to acquire the many skills required of a long-distance cruiser, gets the kids accustomed to shipboard life, keeps you near suppliers and yards and repair facilities and communications facilities and schools, and medical facilities, etc. It also affords the opportunity to work ashore as needed to add to the cruising kitty. And, it affords the chance to decide whether or not the larger goal is realistic and/or still a desirable one.
I've not circumnavigated in a boat myself, but have spent much of a lifetime abroad, including ocean sailing in many diverse locations. In recent years I've cruised from Maine to Grenada, and most places in between. My kids have often accompanied me, and have had extensive experience living and cruising aboard. Kids adapt quite quickly, especially if they're in a friendly environment (such as the Virgin Islands where the water is clear and warm).
In sum, by all means keep the dream alive. And take positive, achievable, reasonable, and responsible steps to achieve the dream just as fast as it feels right to do so.
Just my $ .02