I'd love to stay about 3 1/2 months: October through Early January. If money and time were NO OBJECT but I were limited to WDW, here is my dream plan

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I would start off in Kidani Village in October for about 3 weeks. Spend lots of time just enjoying the animals--slow breakfasts on the veranda, etc; enjoy their pool which really like and I would mostly hit water parks during that warmer time frame. I'd go to the Not So Scary Halloween Party a few times and spend a fair amount of time at AK. We would have to do the Sunrise Safari and the Wild Africa Trek while we were staying there.
Then we would move into the treehouse villas for another 3 weeks. How cool to spend the fall in the forest??? We would spend more time in the parks during that late October/early November time frame as the crowds should be fairly light and the weather comfortable. We would also try to do one of the bigger tours each week (probably Around the World on a Segway, Keys to the Kingdom and Inspiration Through Walt's Eyes).
Around Thanksgiving we would pamper ourselves in the Yellowstone Suite at Wilderness for 3 weeks. We would spend lots of time renting boats, riding horses at Fort Wilderness, visiting the spas, etc. We would mostly take a break from the parks other than popping in for meals and just one or two rides or shows.
We would spend early December up until almost Christmas in the Beach Club Villas. It would be fun to be so close to World Showcase for all of the fun holiday events there. We would enjoy leisurely meals in the various "countries" many nights. I am sure we would want to see the Osborne lights plenty, and head to MK for the Very Merry Christmas Party a couple of times. We could also just enjoy some family time in the villa playing games, etc and enjoy one last time to be able to cook our own meals if we got sick of eating out while at Wilderness Loge. We would get more park time in this slow time as well.
We would finish up by moving into a suite at the Grand Floridian just before Christmas (probably on Dec 21 so we would be there by my son's birthday) and staying until after all King's Day (January 6). Since the parks can be pretty crowded, we would have dinner shows booked for many days, plan on playing mini golf, enjoying Disney Quest, etc and just doing parks now and again when we feel like putting up with the crowds.
I actually think if we did it "right" we would have a lovely tiem and not get sick of it

I obviously have waaaaaaay too much time on my hands to dream about this