The complex is huge... it's over 400 acres in size. Pretty much impossible to do in a one day visit, so they sell 3 day and 7 day packages as well. But, it's also pricey. A one day pass costs $37 USD ($50 CAD). And, you need to be able to get around the complex. We hired a tuk tuk driver to spend the day ferrying us around the various temples for a cost of $20 USD ($27 CAD) including tip. So for two people, $94 USD ($127 CAD). An expensive day out.
We got an early start to try and beat the crowds, and to a certain extent, it worked. We left the hotel just before 8am, and by the time we bought our tickets and walked to the entrance of the main temple, it was 8:30am.