Boy, this could be a long topic.
I think in some respects you will enjoy it more without kids, and in some respects you will enjoy it more with kids.
The without is nice because it is more carefree. It can be a smaller boat. You really get to explore with each other. I am a big advocare of not having kids until you are REALLY ready and have done many things with your life that you enjoy doing as a couple. You can simply be more carefree without kids.
On the flip, as I am sure many here know, we have always had the kiddos with us and I am not sure it will ever be the same without them. I have found that the only thing more fun than snorkeling over a reef is snorkeiling over a reef with my kids for the first time! THe first time they are watching a great barracuda swimming right beside them, or watch an Eagle Ray glide underneath, or dive down holding their breath while the grunts and yellow fins swarm aroun you by the thousands. I have seen so many cool things and the boat felt like more of a home with the kids. THe flip side is that when the kids are young, we had to stay within a reasonable distance of a doctor. THe first storm (or hurricane) you weather aboard with your kids there will put a while new level to the word stress. A nice, quiet evening in the cockpit is a rarity as they want to go fishing. Escaping the kids is almost impossible as you are stuck on a 40 foot boat together.
I believer that taking off and doing long distance cruising with kids on board is a risky factor most are either unwilling to take or try (and find it is too difficult or dangerous for their comfort level). I would suggest honing your skills as a sailor and learning your boat before any long distance stuff. If you ever want to chat about any of this, drop me a pm and I will be happy to discuss over the phone.