I spent 3 days total, which seemed about right to me. This included time visiting the Angkor National Museum, which is not in the complex per se but gives good historical context. I also visited the landmine museum in the complex area. I just used a tuk tuk driver, which was $20-25 or so per day. I got info from the internet and had a book. The Angkor complex is massive. I enjoyed some of the remote sites not only for historical value, but as places for hikes far away from the crowds. If you're an archeologist or something like that, then you can spend weeks there.