Running IV's

Wondering what the standard is in other places doing endoscopic procedures - do you use a hep well when giving sedation or do you give each patient a running IV (rehydrate them a bit and decrease burning of some meds by diluting with the IV)?
We do the hep well and only run IV's on obviously dehydrated/nauseated patients or those with HA's. I'm proposing the running IV's as many of our patients seem fairly dehydrated (esp. colonoscopy patients for obvious reasons). The literature (that I can find) doesn't seem to support this and suggests instead encouraging patients to push fluids until their NPO time (unless medical condition prohibits). Most patients who have to do a 4 liter PEG prep have no desire to drink more! I know PEG isn't supposed to dehydrate, but my experience is that it certainly can.
What do you do?