We stayed for one night during our trip from perth to Nambung Nationalpark in Yanchep. It is so great, that the Yanchep inn is directly in the park - so you can EVERYTIME see kangaroos and koala bears. Especially in the night you can go inside the park and watch hundreds of kangaroos eating, fighting, jumping around (be aware that there are also spiders). In the morning when we opened our room door a kangaroo was sitting outside.
The rooms (or at least ours) was quite old, but you could see that the hotel management is really trying to make the best of it (nicely decorated, made animal figures out of the towels, clean!) The staff is REALLY friendly, they were answering all our questions and you could feel that they are looking after their customers. We also stayed for dinner (there was live musik playing) and breakfast - also really good.
Would defenitly recommend everybody to stay there!!