Note, by days, I'm talking days in one of the 4 main parks. A 7 day trip where you only go to parks 5 days only counts as 5 for the tickets.
For adults, a 7-day non-expiring park hopper, which gets you the same entrance entitlements as the standard annual pass, costs about $12 more after taxes ($370 on AP, $382 on PH, per rates on All-Ears). The difference is those 7 days can span more than a year. But if you are going for at least 7 days during the year, it seems to make more sense for the AP. Plus there are the added benefits (discounts, DDE, etc.)
If you want the Water Parks And More option, then its $483 for the PAP, making the closest non-expiring ticket the 8-day at $475 and the 9-day at $504, so at 9 days the PAP is more effective.
If you don't plan on park hopping ever, then for the no-WPAM option the break-even moves to 8 days, and for WPAM the 10-day is roughly even.