There are SO many ways to make it great! I agree with the other posters...go to AAA or Disneyworld.com and see what deals will be going on then. A lot of times Disney is giving you the dining plan if you stay on property, which makes it well-worth staying there (plus it really isn't any cheaper to stay off property and ruins some of the "experience").
All of the parks are worth visiting since they all offer different things. Depending on how old your other children are, you may want to do some parks more than others (Hollywood Studios has more adult-style rides, Magic Kingdom has more kiddie stuff, etc.).
I also suggest getting the park hopper pass. It costs a little more than the basic one, but it means that you can do more than one park in a day. This will really come in handy when you do Animal Kingdom (we just got back from Disney, and we had finished the entire park by noon...not normal for us, but can you imagine if you were done for the day at noon?). This also ensures that if you want to eat at Epcot every night, you can do this without having to go to Epcot every day!
We do Disney a lot (i.e. I have gone 22 times), if you need any more help, please feel free to private message me! Have fun and good luck!