You're correct about the extended hours: some parks open early in the morning, some stay open later in the evening & just a smidge of research will show you which is which for the week you'll be there.
In my own personal experience, the extra hours aren't worth it, especially the nighttime ones. We're actually avoiding those parks with extended hours for those days altogether as they've proven to be the busiest park on the extended hour days. You've got to think that 11-hour long days are really long, even for adults, let alone kids. Who actually needs MORE time than that for 4 days? Probably nobody.
We're going in July (and are also rockin' the $138 Hopper tickets, gotta love it!!) & have rented a 3 bedroom condo about 10 minutes outside of the main Disney World gate for the whopping price of $495 for the entire week! No amount of extra hours/free transportation could make up that difference in $$ we're saving to us. Because I've saved so much there & also on the park tickets themselves, we're also purchasing 2-day Universal tickets & our trip in full is costing a whopping $2,600 for 2 actual adults & 2 kids who cost as much as adults for everything from tickets, food, condo, gas getting there & back, souveniers, EVERYTHING for a full week. Pretty good if I do say so myself!