Khao Yai National Park

Has anyone visited Khao Yai National park?  We will have car and driver so can organise our own visit.  Most of the organised tours seem to start around 0830, but my experience of seeing wildlife in other countries is that you need to start as early as possible.  The park opens at 0600 and we thought of going to one of the viewing towers as soon as the park opens.  Does anyone else have experience of trying to see wildlife in this or any of the other national parks and how to have the best chance of seeing animals?
We also thought of going back around 1600 to try to catch the animals at dusk.

Been there and not much wildlife visible except for the monkeys sitting at roadside waiting for a handout.

I am also not sure if there is really wildlife to see in Khao Yai park, most people go from waterfall to waterfall and there is not much more to do around there, as far as I know, besides that.

I also have trouble picturing Thais in that park sitting quietly, in the heat, waiting for wildlife to come by. They rather make a million pictures of something less tasteful like what you can find nearby at Palio Khao Yai:
http://stuckinthailand.com/korat/visiti … o-khao-yai

let me know how this go it would be nice to visit the place, heard of vineyards and nice resorts in there...yes, nature watching is fun but haven't heard of wild life and the likes.

If one loves quiet and nature, Khao Yai is a great place to be.  One can stay in vineyard and enjoy grape products - wine, cakes etc.  Its also a great place to cycle around as a good exercise too.  If one book the bungalow with private swimming pool, its a nice place to enjoy with family or friends.