Take a look at the plans for 2009. If you want to do any TS meals (all character meals are TS) then seriously look at the plans. I'm not sure what you mean by well worth the money, but the plans will allow for pre paid meals, taxes are also paid and we had plenty to eat on the 2007 version (1 Snack, 1 TS, 1 Cs/night).
Once you decide the places you're likely to eat add up what you think you'll buy and compare that to the DP rate. The DP is a discount plan its isn't just some trick by Disney to get more money out of you. You will eat at WDW and getting the DP will save money. If you do a plan that included TS meals you need to make ADRs and actually make those meals. If you skip TS meals on those plans you have a greater chance of losing money.
I'm a big fan of the DP.
Just a clarification: if the 9yo is 10 when you start your trip they are a Disney Adult. At 9yo they're still a child and you pay child rates for them and they'll need to order off the child menus.