Hi Danielle!
Thanks for stopping by the Moms Panel and asking us a question!
Both February and September are great months to visit Walt Disney World. I'd have to say that September would most likely have better prices and lower crowd levels (and usually has slightly better weather, in my opinion) PLUS the parks are decorated for Halloween. Most, if not all, of September is usually part of the the value season. The value season prices for Disney resorts mean that prices are among the lowest you'll find. Discounts are often available at at that time as well.
February can be another great time to visit, but there are often peak times at Winter Break vacations for schools in the Northeastern US. Most of the times, the first weeks leading up to Presidents week are lower crowds and prices, but vacations start soon after.
Information on discounts for 2012 are not yet released, but the announcement of the free dining promotion for 2011 was in the fall of 2010. You'll want to keep an eye on the
Special Offers page of Disneyworld.com for announcements on discounts. Its also important to note, that if you have an existing reservation with Disney, you are often able to apply a newly released discount to your account. This means that most times you can go ahead and book your vacation when you are ready to, and then continue to keep on top of discounts as they are released.
Hope you have a great time planning your Disney vacation and be sure to let the Moms Panel know if we can help you with any more trip details!