Is there some sort of discount on admission prices after a certain time during the parks operating day? For example, maybe after 6 o'clock tickets are half price. I can't seem to find this on the PKI website, nor have I seen it advertised anywhere around the park (Granted, I haven't looked too hard either.)

Yes tickets are discounted heavily after a certain time. For some reason I do want to say it's around 5 or 6 PM.

It's called a Starlight Ticket and I thought that it began at 4pm, but I could be wrong. You may want to call their park operations to find out for sure.

It might depend on who you buy your tickets from. I got mine from AAA at a sale price (which ended last Tuesday) of $20.00 for a one day ticket with after 5pm night before admission option for $10.00.

after 5:00 tickets are $25.99 and through AAA you can buy a special ticket where if you are going in the park a whole day, then you can get in the park for $10.00 the night before. (after 5:00).