$1500 is more than enough for 5 adults & a child to eat on at Disney, IMO. I do agree to go check out allears.net and see what the menus look like (along with the pricing) for the places you are thinking about eating.
As for the dining plan not being a good deal for character meals... not ALL character meals are breakfasts. We did all dinners (except 1 breakfast) on our last trip, and they were all character meals.
Also, know that most of the character meals ARE buffets, and the pricing is flat rate. However if you go to another resturant you can easily share a meal (the portions are HUGE) and save some $$ that way. Plus, the CS meals can easily be shared as well, and by being CL you have snacks at your disposal, so the snack credits would be futile if you were on the DDP (unless of course you wanted something while inside the parks).
Another option would be to get the QSDP rather than the DDP, and use your GC's to pay for a couple of sit down meals (and the tips, and a bunch of other fun stuff as well). Don't forget that you can upgrade your park tickets at the ticket gates once you've arrived (to add the park hopper option, additional days from the base 5 day that is required for the GC offer, or the water park option) and use your GC that way as well.
I hope this helps you! If you are going for more than 8 days, you might be stretching it on $1500 (that's less than $200/day) if you were wanting 1 sit down meal each day. If it is 7 days or less, I really think you will be fine.
