My gut reaction is WL, CL or not. The resort is so peaceful and serene. I could easily sit outside in a rocking chair reading a book and listening to the waterfall and be perfectly content. Plus, they now have the poolside spa, and the lakeside restaurant where you could watch some college football (if you're like me and like to catch up while on a September WDW getaway...). Plus, it is so easy to take the boat over to Ft WIlderness and do the activities there, or over to the Contemporary to hop on the monorail for a ride. And, I agree with the above posters, there is nothing better than being able to walk straight downhill out of MK at the end of a long day and hop right on a boat to the resort. It cannot be beat.
CL at WL is great. The food is defeinitely enough to keep you satisfied, and the fireworks from MK at night are fun to watch from the balcony.
I must admit, I have not stayed at YC, but I recently stayed at BC in CL, and I assume the experiences would be very comparable. I thought the CL was great. However, I did not think the hotel itself had much going on. The pool was nice, but not nearly as exciting as people had talked it up to be. The real pro was walking to Epcot and boating to HS, but since you aren't going to Epcot or HS, I actually think it would be kinda hard to be that close and not go?? There is the Boardwalk, and it's cute. But, it's mostly restaurants, so unless you're going to be constantly eating, it will not fill up much time?? I guess you could sit on a rocker outdoors there too, but it is not nearly as serene watching people walk along the path to and from Epcot as it is at WL overlooking a waterfall into Bay Lake. Plus, you get the Electric Water Pageant on Bay Lake ;-)
CL at BC had great food, but that's all it really offered?? dThere was no way to watch the fireworks or shows from Epcot or HS. Not sure if there is at YC CL?