Walt Disney World vacation in October?

I am wanting to go for 3 weeks, is this a good amount of time for me to get better deals rather then going for 2 weeks?
I have found out by most travel agencies that 2 weeks is the amount of time packages are set up.
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Also we( 2 of us) want to stay inside the park so we can have quick access to the resorts and parks.
Are there any sites that have peoples feedback about these hotels/resorts and what they all experienced?
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vacation to Disney