I agree with Renysmom that you have to look at what you're getting for your dollar and if it's worth it to you. $1500 a day is a lot of money, but what would an equivalent experience cost you? Say you went to another city for a holiday. Most of the time a nice room will cost you at least $200 a night, so there's $400. Add a standard buffet breakfast, ($15 per adult, $10 per child) = $80, burger type lunch ($10 each)=$60 and a nice, elegant three course dinner ($50 per adult, $25 per child) = $250. Soft drinks and snacks can easily add another $10 per person. So that makes $750 for just the basics.
A broadway style show will run you at least $80 per ticket ($480+) and kids camps or child care is at least $50 per kid for a pretty short day. And good luck finding a program that will please a range of kids from three to seventeen! Add evening babysitting and you're looking at $15 to $20 per hour.
So, in short, a cruise can be good value, even at the higher rates. But if you're looking at that and thinking that your family doesn't even like shows, or would never go out to fancy restaurants while on vacation, or your kids would rather hang out with you and wouldn't like the clubs, well you may not feel like you've got your money's worth.
Now the question of whether
DCL is worth a lot MORE than other cruise lines, well that's a tricky one. We've cruised other lines and I personally think its worth more, but not by a huge amount. If I could get a seven night on RCL for the price of a four night on Disney, I think I'd go for the seven night. But I think that since you're experienced both with Disney and with cruising in general, you're pretty well set to make that decision. Not that it will make the decision any easier!
Oh and one last thing, if you do really want to cruise Disney, make sure you do it before your oldest turns 18. It sounds like the older teens get the short end of the stick as far as activities go!