I just did this a couple of weeks ago. Take the train. Very fast and comfortable. Then catch the metro or cab to the hotel. Total travel time was about 3 hours door to door.
The train departs from Hung Hom which isn't very far from the Sheraton and arrives into East Guangzhou station. You can buy tickets at the station or have the concierge buy it for you in advance.
I'm not Hong Kong based, so I have only the regular crew visa, and I had absolutely no issue with immigration into China