Have a great vacation! A few thoughts..
Dining Plan Choice and Signature DiningIf you really want to do more signature dining and shows (2 credit places), consider if the deluxe dining plan is better for you. For us, the cost to go deluxe was not much more than the Plus
DDP. We enjoyed doing all our dining table service, it was fun and a welcome break for our feet. We like appetizers (included with deluxe), there's more snack credits, and the refillable resort mugs are included. We like the signature restaurants - especially Flying Fish Cafe, California Grill, and Brown Derby.
Shows? Have you considered the shows? Like Spirit of Aloha, Mickey's Backyard BBQ, or Hoop Dee Doo? All 3 are different. For young children, I'd recommend Backyard BBQ. But we like all 3.
Hollywood and Vine I'd keep it but change it to breakfast. The breakfast food was just fine, very good actually. (It's hard to mess up breakfast!) And the best character interaction -- Agent Oso, Handy Manny, a couple of the Little Einstein characters will dance with the children almost non-stop to Playhouse Disney Music, and they still do table greetings. Many character meals are just the table greetings. I agree that Lunch and Dinner (no characters at dinner) food was not good -- think of a low budget buffet like Golden Corral.
1900 Park Fare Dinner If you want to see Cinderella and Prince Charming, Lady Tremaine and the step sisters.... this is an easy way to do it. But it was pretty crowded in there. LT and the step sisters are much more fun to interact with in the park - more room and ability to joke around.
Character Meals -- We will continue to do character meals because it's an easy way to meet them without standing in a line. But, if you just want to meet the characters, you can find most of them in the parks too (but not sure about Agent Oso). But there may be lines and timing is important. Mickey is everywhere. Epcot's character spot is good for Mickey, Minnie, Donald, Pluto, and Goofy? all in a row. Hollywood Studios has sorcerer Mickey all the time. Animal Kingdom has the same Tusker House characters at Mickey and Minnie's greeting trail by the Lion King Show. The one character meal I do value is Crystal Palace (good food and the pooh characters never seem to be out all at once in Magic Kingdom). And Garden Grill (Chip and Dale seem to be hard for us to find anywhere else). And Ohana breakfast if you like Lilo and Stitch. Epcot has lots of characters around the world (timing is important) and the princesses and fairies are in Magic Kingdom (can be long lines). 1900 Park Fare Breakfast has the Mad Hatter, Alice in Wonderland, and Mary Poppins who can be hard to find... (Alice and Mary P are in Epcot I think... again timing is important.)
Ohana - This is one place I will not return to. It gets a lot of hype in the reviews but for us, the check-in process and long wait was aggravating. The food quality in 2010 went downhill compared to 2009. Just not worth it when there are so many better places to eat. You can read my review to get more info (link below).