I went in October 2005 and plan to return the same time this year. I really like that time of year! Not only do you have the Halloween party, but you also have the food and wine festival at Epcot!
There were four women in our party (no kids) and we really enjoyed the Halloween party. The parade is fantastic (picture the Winnie the Pooh characters dressed in Halloween costumes - Eeyore was dressed as a mummy - too cute!). Just the fact that you could literally walk onto any ride was worth it for us. Plus, the park is much less crowded than on a typical day. We plan to go to the Halloween party again this year. I definitely recommend it, even though it costs extra.
Definitely plan to go to the food and wine festival. We had park hopper passes, and "hopped" to Epcot literally every day. I don't even drink wine, and had a great time! My friends went to the tastings and classes about wine, and while they were doing that, I went off on my own to explore.
Have fun!