Another poster mentioned the amount of things to do outside of the parks. This actually reminds me of a trip I am planning in my mind (one of many; I have anywhere between 4-8 trip ideas going at any given time).
I like all four parks. There's something special at each of them. However, I sometimes don't want to deal with as much hustle and bustle and instead want a nice place to go to after a long stretch of work. I'm self-employed and often will be working 50-60 hours per week.
Therefore, in this version of my Disney trip, I stay four nights at Yacht Club. That's already around $1500, give or take. However, it gives me the best pool of them all and essentially gives me a pseudo-beach, smaller but chlorinated and without dead fish. It also gives me a lot of options as to what to do around there.
I figure to spend a lot of time at the pool and spa area, but couldn't do that all day, of course. On one day, I'd rent a boat. It may not be at that area, since the sailboats are near Grand Floridian, but considering I usually drive an hour to go sailing here in Pittsburgh, it's not a big deal. Plus, I could rent something bigger than the 12.5' dinghy I take on the lake here just to have some fun, maybe a Flying Scot or similar boat.
There's also golfing. I could spend a day at the golf course, too.
At night, there's the Boardwalk area. There's Jelly Rolls, the dance hall, the ESPN club. Note that I haven't even ventured into a park yet here. Let's also not forget my favorite restaurants are all around there--Yachtsman Steakhouse, Flying Fish, Cape May Cafe, Beaches and Cream, and the Italian place that used to be Spoodles.
Notice how we have two of the three complete days already filled. The boat rental and golfing would be about the same as a park ticket, but would be more on par with what I'd pay locally--yet wouldn't be Lake Arthur or any of the golf courses in Pittsburgh.
Now...my favorite park is MGM. It's also within walking or boating distance of Yacht Club. I'd buy one pass for that park so I could go there for a day on this trip. I wouldn't mind paying more here since it would be the only park I'd be going to. I'd pay $125-130 for it without complaining since I wouldn't have gone to any other park.
I'd really have to milk that day at MGM. Yes, it's small even with Toy Story Land open, but there's plenty of in-street entertainment, restaurants I always enjoy (50s Prime Time and Sci-Fi, plus the Hollywood Brown Derby), Fantasmic, and my all time favorite attraction anywhere at WDW, Tower of Terror.
"But what about the other three parks?" If this trip is purely for relaxation, I don't have to deal with the crowds or longer walking distances that are present at the other parks. Plus, if I'm going to go just to chill, I'd rather spend money on a boat or golfing, and those prices, while perhaps higher than other boat rentals or golf courses, would be more worth it to me in that particular moment than a park. Don't get me wrong, I love the parks, but they're not always super-relaxing now that I'm in my thirties (and don't have children).
The trip may not seem as Disney-like without them, but the money invested into a good hotel, golfing, sailing, dining, and the park that I like the best would make it arguably the most relaxing vacation a thirty-something could take, not to mention it's a safe, clean environment.
(Disclaimer: I am fully aware the park is now called Hollywood Studios, but MGM is so much quicker to type and it's what I grew up calling the park!)