If you are attending a convention at WDW, as we just did, then you are given the opportunity to purchase after-2pm and after 4-pm tickets. I figured out the pricing and it was only a few dollars more to purchase the whole day ticket. Sounds odd but that was the case. I can't access the link anymore, but I know it wasn't a great discount. You can also purchase water park options or hopper options. And also, those tickets do expire within 7 days (I think).