Our access to Khao Yai National Park was through the Northern gate. As far as I know there are 2 gates that you can enter, one in the South and one in the North. All the accommodation within the park was full so we stayed in a Guest House just a few km from the gate, called Bann Kroo. Rooms in Bann Kroo cost us 300B per night and were small and simple but nice and exactly what we wanted. I thought it was a nice place and the owners were good people and I would recommend it for a simple, no fuss place to stay. There are many places to stay outside the park as well as accommodation within the park. However, within the park, the accommodation is often booked out on weekends and public holidays, so it is best to book in advance or be prepared to not stay in the park if you are there on a weekend / holiday.