I really liked the service at Bumrungrad last time. You change clothes and then get a private little room with an easy chair, a TV and a toilet. They bring you all the stuff you have to drink at tell them when your "stool" is clear. Very easy, and about as pleasant as one could hope for.
The previous scan (also at Bumrungrad) they gave me the stuff to take home, to drink at home and come in after the stool is clear. That was not a pleasant experience.
If cost is a big concern, I would use a different hospital, but I would only use one that uses the system described in the first scenario.
The doctor was great. Had trained in the US and spoke excellent English.