I am a OCVP (Obsessive Compulsive Vacation Planner). On our first trip to WDW, my youngest were the same ages as your kids. We brought a friend with us so we had three adults with three kids. We were on a Make A Wish trip, so we didn't have to stand in line AT ALL -- (Imagine WDW without lines). And the youngest still got overwhelmed/tired/wanted to go back to the resort and pool. DS4 was still too small to enjoy many of the rides (like Splash Mountain) and was scared by others.
The next trip we planned 8 days at WDW. We relaxed, spent part of the days in the park, more time at the resort, less time trying to see everything, Downtown DIsney one night, mini-golf, etc. It was more relaxing and the kids enjoyed it a lot. Even with lines. My wife reminded me that this is VACATION and that we want to come back relaxed and feeling like we had a break.
DCL means being able to move very easily at the children's pace. They can go to the clubs, swim -- my DS11 thought 11:00 PM swims in the Mickey pool by himself were great, eat when you want without worrying about the fact that they changed their minds and only wanted three fries because they just saw Mickey walk by, etc.
The parks have plenty to do for children. But you will have to be willing to give up going to things that you want to do (Haunted Mansion, Mountain rides, etc.), and work at their pace. I remember the revolt I had in my family because I wanted to see the fireworks after a long day in the park, ouch, that one still smarts.
Every family is different, but I would wait for your children to be older for WDW -- I think early elementary is ideal. And then enjoy the cruise and the relaxing on the ship now (the most stress I saw were the families standing in line for character meets).
Just my opinion,
-- JimV