There are several nuances to what has already been posted.
IMHO, the most difficult reservations to get also depend on the resort and the date. For example, IMHO, the most difficult reservation to get is a standard view studio at the BWV for New Year's Eve.
In fact, if you want to stay in standard view units or guaranteed Boardwalk view units between Thanksgiving and December, you need to call day by day as soon as MS opens to be sure of getting it without having to use the waitlist.
In general, dedicated 2 bedroom units at the BCV are also very difficult to reserve without taking full advantage of the 11 month window, no matter what time of year you visit. Also tough without the home resort advantage are (in no particular order):
* Grand Villas anywhere, including the Beach Cottages at VB
* The already mentioned SV & guaranteed Boardwalk view units at the BWV, * Studios & 1 bedrooms during the summer at HHI
* All room types at VWL between Thanksgiving & New Year's Day
* All room types at BCV & BWV starting with Food & Wine Festival time and continuing all the way to New Year's Day
* Conceirge rooms & value rooms at the AKV - just speculating as we don't have any expeirience with these yet.
I've probably missed some. Please note that it is POSSIBLE to get accomodations at 7 months that meet the above criteria (if you know & use the system to the max), but the odds are not in your favor and you may need to use the waitlist to be successful. (Thus the advice to buy where you want to stay the most or at least buy where you won't be disappointed to stay when you can't get something else at 7 months).
As the membership grows, the competition at the 7 month mark will just continue to increase.