Hi Amy,
Any time of the year is a perfect time to visit Walt Disney World, but I particularly enjoy October. Generally, the weather is cooler and the crowds are less than it is in the summer and there are some great special events. Historically, the Epcot International Food and Wine Festival is held from the beginning of October through mid-November. I love sampling the different foods from around the world!
Mickey's Not So Scary Halloween Party also occurs during that time frame. In 2009, there were dates for the party from the first week of September through November 1st. Based on how much fun I see other young kids having, I think your girls will love it. Disney has not released dates for the party for 2010 yet, but you can keep checking back
here throughout the year.
Disney has a lot of great resorts and I think if you ask any two people which are the best, you would most likely get a different answer. My absolute personal favorite is Disney's Wilderness Lodge. It is a Disney Deluxe resort and is on the lake behind the Contemporary. The theming is fabulous and there is boat service to the Magic Kingdom; that may be useful to you if you go to the Halloween Party as I believe the line for the boat is much less stressful than the line for the monorail at park closing. My 10 year loves the Beach Club because of Stormalong Bay, the amazing sand bottom pool there. It's like have a mini-water park at your resort! My 5 year old thinks the Animal Kingdom Lodge is fabulous! He loves watching the animals at the resort. For a Moderate resort, my family loves Port Orleans Riverside.
Enjoy planning your next trip and be sure to write back if you have any more questions!