As an installer, I can say that a tip in general not expected and doesn't happen that often. However, when it does happen, we are very grateful. Of course, that's here in AZ and most markets. Las Vegas was a different story. People dropped tips on me all the time there, I guess it's just because Vegas is the tippin' town. If you don't like to tip but feel you want to do something for the installer, there are a few things you can do. If they are an inhouse tech, you can purchase an ancillary product. In fact, that might be worth more to the tech than what you would tip. If you happen to be that sale that puts him in the next bonus level, it could be worth a few hundred bucks to that tech. Also, do the survey call and give the tech a good score. Now, if your tech is a subcontractor, anything that can save him time will be a benefit for them as they are often paid by the job. This is where you can help out by having all the TV sets, entertainment centers, etc., moved a few feet away from the wall before they get there. Look around the outside of the home, are there any objects that he is going to have to move just to run wires that you can get out of his way beforehand? Bushes you can trim back? Make sure to have all the TV remotes handy. If it's hot out, keep the water coming. It might not be that hot to you but for a guy working his tail off, even 75 degrees out can be pretty hot.
If I can see that you've done some prepping for the appointment by doing the above, I will be just as grateful as if you tipped me because you will have got me home sooner or got me the time needed to pick up more work.
PS: If you are getting internet installed too, it would be better to get that installed first so that we have more connectivity options. That will help our numbers out when trying to make bonuses, etc. It also means the cable guy won't be behind us, taking our line for their purposes, forcing us to come back and messing up our numbers.