I'm not sure of sites that would list prices per day, but generally on site prices go up for weekends. I would suggest playing around with dates, also try a couple of 3rd party booking sites (I use Orbitz for Disney hotels, managed a 20% discount for our trip). The more you look the better you understand pricing, and the quicker you can react when you see a good deal.
On site is awesome, all 3 hotels are great, pricing is pretty fair for what you get from each. PPH is the cheapest and feels it, kinda like a standard hotel with Disney theming, but still a really nice place to stay with the added perk of EMH and quality Disney service. DLH has wonderful theming and is, of course, the original. GCH is subdued and luxurious and a killer location, but the price brings tears to the eyes and trauma to the credit card!