There are a few other upsides to doing your service at a dealership which haven't been mentioned..
Some of these may just apply to my store though..
For new car customers - we pick up the customers car, do the service, drop it off. No extra charge. Free Maser loaner if needed.
Competent technician servicing the car, who also does a quick road test during every service. They will know better than anyone else if there are any other minor issues creeping up, while they are still minor. Little sounds, or hesitations, or even visual things that an owner may not notice (or see if its under the car). They know the car inside and out, since it was new. They will also know any other minor little issues, similar to stuff that we find here on the forums, and will know to tell you whether you need to have something else checked out or not.
my $.02
- Mark